EP0278366B1 - Dispositif de commande du braquage des roues d'un véhicule - Google Patents

Dispositif de commande du braquage des roues d'un véhicule Download PDF

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Publication number
EP0278366B1
EP0278366B1 EP88101474A EP88101474A EP0278366B1 EP 0278366 B1 EP0278366 B1 EP 0278366B1 EP 88101474 A EP88101474 A EP 88101474A EP 88101474 A EP88101474 A EP 88101474A EP 0278366 B1 EP0278366 B1 EP 0278366B1
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EP
European Patent Office
Prior art keywords
vehicle
iii
steering
output
signal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
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EP88101474A
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German (de)
English (en)
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EP0278366A1 (fr
Inventor
Mizuno Masahiko
Amano Nagakute-Ryo 412 Yasushi
Yasuda Eiichi
Doi Shunichi
Hayashi Yasutaka
Yamaguchi Nagakute-Ryo 701 Hiroyuki
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Toyota Central R&D Labs Inc
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Toyota Central R&D Labs Inc
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Priority claimed from JP62023261A external-priority patent/JP2551770B2/ja
Priority claimed from JP62284046A external-priority patent/JP2562626B2/ja
Application filed by Toyota Central R&D Labs Inc filed Critical Toyota Central R&D Labs Inc
Publication of EP0278366A1 publication Critical patent/EP0278366A1/fr
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Publication of EP0278366B1 publication Critical patent/EP0278366B1/fr
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D7/00—Steering linkage; Stub axles or their mountings
    • B62D7/06—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins
    • B62D7/14—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering
    • B62D7/15—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering characterised by means varying the ratio between the steering angles of the steered wheels
    • B62D7/159—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering characterised by means varying the ratio between the steering angles of the steered wheels characterised by computing methods or stabilisation processes or systems, e.g. responding to yaw rate, lateral wind, load, road condition
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
    • B62D5/061—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle provided with effort, steering lock, or end-of-stroke limiters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2400/00—Indexing codes relating to detected, measured or calculated conditions or factors
    • B60G2400/80—Exterior conditions
    • B60G2400/84—Atmospheric conditions
    • B60G2400/841—Wind

Definitions

  • the present invention relates to an apparatus for controlling steering of wheels of a vehicle and, more particularly, to an apparatus for controlling steering of wheels of a vehicle in which a high correction capability of variables representing vehicle behaviors is provided against disturbance such as side and gusty winds, and high response for changes in vehicle behaviors in response to a steering input such as rapid steering or vehicle turning with a large radius.
  • Traveling performance and steering stability of a vehicle primarily depend on a yaw rate (i.e., angular velocity generated around the center of gravity when the vehicle is viewed from the top) of the vehicle responding to a steering input, i.e., a steering wheel operation, or a lateral acceleration (i.e., an acceleration acting on the center of gravity of the vehicle in a direction perpendicular to the vehicle traveling direction, i.e., an acceleration parallel to the traveling direction of the vehicle).
  • a yaw rate i.e., angular velocity generated around the center of gravity when the vehicle is viewed from the top
  • a lateral acceleration i.e., an acceleration acting on the center of gravity of the vehicle in a direction perpendicular to the vehicle traveling direction, i.e., an acceleration parallel to the traveling direction of the vehicle.
  • Japanese Laid-Open Patent Publication 60-161266 corresponding to EP-A- 0150 857 describes an apparatus obtained by combining feed forward control and feedback control.
  • the first method is to control traveling performance and stability by a value obtained such that a differential value of a difference obtained by subtracting a coefficient multiple of a yaw rate or a lateral acceleration from a steering wheel angle is added to the difference, as shown in Fig. 2.
  • the second method is practiced as follows, as shown in Fig. 3. A value is obtained by multiplying a coefficient with a differential value of a steering wheel angle and is added to the steering angle to obtain a sum. The sum is used as a feed forward signal for auxiliary steering of the rear wheels, and the vehicle behaviors are used as a negative feedback signal for auxiliary steering of the front wheels. The drawback of feedback control is canceled with that of feedback control.
  • auxiliary variables representing vehicle behaviors are rapidly increased by a control value influenced by the differential value, and the vehicle is rapidly turned.
  • Heavy mental load imposed on the driver is caused by rapid vehicle turning.
  • the driver excessively turns the steering wheel, the vehicle loses stability, and a traffic accident may occur.
  • the differential value is rarely influenced on the vehicle behaviors.
  • the feed forward signal is decreased, and understeering in the vehicle is caused as a whole. As a result, traveling performance of the vehicle is degraded.
  • the above disadvantage of the conventional auxiliary steering apparatus is caused by feed forward control using a steering wheel angle and a value obtained by multiplying a differential value of the steering wheel angle with a coefficient.
  • the influence of the differential value is increased as compared with the normal steering apparatus, and desired control cannot be performed.
  • the coefficient multiplied with the differential value is decreased, a total gain is reduced and the control system in the vehicle is substantially the same as that of feedback control.
  • Optimal control cannot be performed by the above-mentioned auxiliary steering apparatus.
  • the disadvantage of the prior art is based on simple use of two values, i.e., the steering wheel angle and the value obtained by multiplying the coefficient with the differential value of the steering wheel angle in feed forward control.
  • the present inventors also took values as coefficient multiples of the steering wheel angle into consideration in addition to the above-mentioned two values in feed forward control.
  • the present inventors found that a combination of feed forward control and feedback control provided better traveling performance and stability.
  • Understeering of the vehicle can be reduced by the values of coefficient multiples of the steering wheel angle when the vehicle is turning with a large radius. Stability in feed forward control can be assured without degrading dynamic characteristics of the vehicle. Auxiliary vehicle steering having high resistance to disturbance and a short response time can be achieved.
  • the steering control system can be operated to suppress changes in vehicle behaviors. For example, magnitudes of signals for state variables representing vehicle behaviors are compared with respect to the steering angles in the rough and smooth road surfaces. Friction values ⁇ are estimated by the above comparison operations, and the gains of the yaw rate feedback system are controlled using the estimated friction values. The changes in vehicle behaviors such as the yaw rate can be therefore decreased.
  • the gains of the coefficient circuits in the feedback and/or feed forward control system are reduced to eliminate the influences of the above-mentioned problems.
  • an apparatus for controlling steering of wheels of a vehicle, or controlling variables representing vehicle behaviors comprises : a steering sensor I for detecting a steering angle of a steering wheel ; vehicle behavior sensor II for detecting the variables representing vehicle behaviors ; a control means III comprising a feed forward signal operating means III 1 , a feedback signal operating means III 2 , and a control signal operating means III 3 , the feed forward signal operating means III 1 being provided with a steering angle signal circuit III 11 for outputting a steering angle signal outputfrom the steering sensor without processing, a steering angle signal operating circuit III 13 , a steering angular velocity signal operating circuit III 16 , an adder 111 17 for adding signals output from the steering angle signal circuit III 11 , the steering angle signal operating circuit III 13 , and the steering angular velocity signal operating circuit III 16 , and the steering angle signal operating circuit III 13 being further provided with a first coefficient circuit III 12 for multiplying the steering angle signal with a coefficient G 1 , and the steering angular velocity signal operating circuit III 16 being further provided with
  • the above-mentioned apparatus for controlling steering of wheels of a vehicle has the following functions and effects.
  • the steering sensor I the steering angle of the steering wheel is converted into an electrical signal corresponding to the steering angle.
  • the vehicle behavior sensor II the variables representing the vehicle behaviors are converted into electrical signals and the like corresponding to the variables representing the vehicle behaviors.
  • the electrical signals output from the steering sensor I and the vehicle behavior sensor II are processed in the control means III.
  • vehicle controllability for steering is improved by generating a signal representing a control steering angle exceeding the measured steering angle. This signal is generated by the feed forward signal operating means III 1 .
  • the feed forward signal operating means III 1 comprises the steering angular velocity signal operating circuit III 16 provided with the differentiator III 14 and the second coefficient circuit III 15 to differentially increase or decrease the steering angle, the steering angle operating circuit III 13 provided with the first coefficient circuit III 12 to correct the magnitude (coefficient G 1 ) of the measured steering angle, and the steering angle signal circuit III 11 » for supplying the steering angle to the control means without processing.
  • the feedback signal operating means III 2 comprises the vehicle behavior signal operating circuit III 22 provided with the third coefficient circuit 111 21 for multiplying the coefficient G 3 for determining the feedback amount with the signal from the vehicle behavior sensor II for detecting the variables representing the vehicle behaviors. Therefore, stability of the vehicle can be improved.
  • a steering angle 8 of the steering wheel is converted into a feed forward signal having a value of ⁇ +G 1 - ⁇ +G 2 8 by the feed forward signal operating means III 1 .
  • the feed forward signal and the signal generated by the feedback signal operating means are subjected to an addition or subtraction in the control signal operating means 111 3 , thereby generating the steering control signal.
  • the driving means IV amplifies the steering control signal into an actuator drive signal for driving the actuator.
  • the actuator drive signal is used to drive the actuator in the actuator means V so as to apply an optimal steering angle to at least one of the front and rear wheels.
  • the feed forward signal is obtained by multiplying the differential value of the steering wheel angle with the coefficient G 2 .
  • the steering wheel angle 8 and a differential value 8 of the steering wheel angle are output.
  • the vehicle is rapidly turned to cause an unexpected behavior.
  • the driver must turn the steering wheel in a complicated manner.
  • the influence of the differential value ⁇ is canceled by a value of a coefficient multiple of the steering wheel angle 8, thereby assuring steering stability.
  • the value of the multiple of the steering wheel angle coefficient can be subtracted in addition to an addition of the differential value of the steering wheel angle so as to prevent abrupt turning of the vehicle when the driver abruptly turns the steering wheel. Abrupt behaviors of the vehicle can be suppressed. As a result, the mental load on the driver can be reduced, and safety driving can be assured.
  • the apparatus can be quickly operated in only the initial period of abrupt turning.
  • the value of a coefficient multiple of the steering wheel angle can be added. Understeering of the vehicle can be reduced and safety can be assured under feed forward control without degrading the dynamic characteristics of the vehicle. Therefore, auxiliary steering of the vehide which is substantially free from disturbance and highly responsive can be performed.
  • the value of the coefficient multiple of the steering wheel angle is subtracted to reduce the influence of the differential value, thereby assuring a safe behavior of the vehicle.
  • the first mode of the present invention is shown in the block diagram of Fig. 4.
  • a control means III is connected to a vehicle state detection sensor IV and a first coefficient circuit III 12 .
  • the vehicle state detection sensor IV detects vehicle travel state variable with the vehicle travel such as a vehicle velocity, a vehicle load, a wheel load, a vehicle wheel velocity, a vehicle wheel angular velocity, a road surface shape (e.g., sprung relative displacement and velocity), and so on.
  • the control means III comprises a gain changing means 111 4 for changing a coefficient of the first coefficient circuit 111 12 on the basis of the signals for vehicle travel states.
  • a steering sensor I detects a steering angle of a steering wheel and generates an electrical signal corresponding to the steering angle.
  • a vehicle behavior sensor II detects a change in variables representing a vehicle behavior and generates an electrical signal corresponding to the change.
  • the vehicle detection sensor VI detects the vehicle travel state such as a vehicle velocity, a vehicle load, a wheel load, and a vehicle wheel velocity and generates electrical signals corresponding to these state variables.
  • a feed forward signal operating means III 1 comprises a steering angle signal circuit III 11 for outputting the steering angle without processing, a steering angle signal operating circuit III 13 provided with the first coefficient circuit III 12 for correcting a magnitude (i.e., a coefficient G 1 ) of a steering angle for the detected steering angle, and a steering angle velocity signal operating circuit III 16 provided with a differentiator III 14 for differentiating the steering angle and a second coefficient circuit III 15 .
  • the feed forward signal operating means III 1 in the control means III converts the input steering angle 8 into a feed forward signal ⁇ +G 1 . ⁇ +G 2 . 8 and a steering angle exceeding the detected steering wheel angle is applied to shorten response time of the vehicle.
  • a circuit III 2 for operating variables representing vehicle behaviors having a third coefficient circuit III 21 for multiplying a signal from the vehicle behavior sensor II with a coefficient G 3 for determining a feedback value
  • the vehicle behavior state variable a is converted into a feedback signal G 3 . a.
  • the feedback signal is used to suppress the abrupt change, thereby stabilizing traveling of the vehicle.
  • a difference between the feed forward signal generated by the feed forward signal operating means and the feedback signal generated by the feedback signal operating means is calculated by an adder/subtractor III 31 in the control signal operating means III 3 to generate a steering control signal.
  • the steering control signal is amplified by the driving means IV as an actuator drive signal for driving the actuator.
  • the actuator drive signal is used to drive the actuator in the actuator means V so as to apply an optimal steering angle of either the front or rear wheels or both.
  • the gain changing means 111 4 can change the coefficient (to be referred to as a gain G) G 1 of the first coefficient circuit III 12 on the basis of the signals for vehicle travel state variable with the vehicle travel, such as a vehicle velocity, a vehicle load, a wheel load, and a vehicle wheel velocity, output from the vehicle state detection sensor Vl.
  • the gain G 1 of the first coefficient circuit 111 12 can be changed in accordance with the vehicle states such as a vehicle velocity, a vehicle load, a wheel load, and a vehicle wheel velocity. Even if the vehicle velocity is changed, the controllability for the behaviors for steering of the vehicle can be kept constant. Therefore, vehicle controllability and vehicle stability can be improved.
  • the second mode of the present invention is shown in the block diagram of Fig. 5.
  • a control means III is connected to a vehicle state detection sensor Vl for detecting vehicle travel state variable with the vehicle travel, representing the vehicle, such as a vehicle velocity and a vehicle load and/or an outside environmental situation detection sensor VII for detecting an outside environmental situation such as a road surface condition and a first coefficient circuit III 12 .
  • the control means III comprises a gain changing means III 4 for changing a coefficient G 1 of the first coefficient circuit III 12 on the basis of signals for vehicle travel state variable with the vehicle travel and output from the vehicle state detection sensor VI and/or signals for state variables representing outside environmental situations and output from the outside environmental situation detection sensor VII.
  • a steering sensor I converts a steering angle of a steering wheel into an electrical signal.
  • a vehicle behavior sensor converts a vehicle behavior state variable into an electrical signal.
  • These electrical signals from the steering sensor I and the vehicle behavior sensor II are processed in the control means III so as to optimize the vehicle behaviors for the steering angle. More specifically, a feed forward signal operating means III 1 converts a steering wheel angle 8 into a feed forward signal ⁇ +G 1 . ⁇ +G 2 . ⁇ .
  • the feed forward signal generating means comprises a steering angular velocity signal operating circuit III 16 provided with a differentiator III 14 for differentiating the steering angle and a second coefficient circuit III 15 , a steering angle signal operating means III 13 provided with the first coefficient circuit III 12 for correcting a steering angle magnitude of the detected steering angle, and a steering angle signal circuit III 14 for transmitting the steering angle without processing to the control means.
  • a circuit III 22 for operating signals for variables representing vehicle behaviors having a third coefficient circuit III 21 for multiplying a signal from the vehicle behavior sensor II with a coefficient G 3 for determining a feedback value, the vehicle behavior state variable a is converted into a feedback signal G 3 . ⁇ .
  • a difference between the feed forward signal generated by the feed forward signal operating means and the feedback signal generated by the feedback signal operating means is calculated by an adder/subtractor III 31 in the control signal operating means III 3 to generate a steering control signal.
  • the steering control signal is amplified by the driving means IV as an actuator drive signal for driving the actuator.
  • the actuator drive signal is used to drive the actuator in the actuator means V so as to apply an optimal steering angle of either the front or rear wheels or both.
  • the gain changing means 111 4 can change the coefficient (gain) G 1 of the first coefficient circuit 111 12 on the basis of the signals for vehicle travel state variables with the vehicle travel, such as a vehicle velocity, a vehicle load, a wheel load, and a vehicle wheel velocity and/or the signals for state variables representing outside environmental situations such as a road surface condition.
  • the gain changing means 111 4 changes the gain G 1 on the basis of the vehicle velocity, the vehicle load, and the road surface condition, all of which are represented by the electrical signals corresponding thereto and output from the vehicle state detection sensor Vl and the outside environmental situation detection sensor VII, the response characteristics of the vehicle behaviors for steering can be kept constant event if the vehicle velocity is changed, thereby further improving vehicle controllability and vehicle stability.
  • the third mode of the present invention is shown in the block diagram of Fig. 6.
  • the gain changing means III 4 is connected to the first coefficient circuit III 12 and the second coefficient circuit III 15 .
  • the coefficients in the first and second coefficient circuits III 12 and III 15 are changed on the basis of the signals for vehicle travel state variables with the vehicle travel and output from the vehicle state detection sensor and/or the signals for state variables representing outside environmental situations and output from the outside environmental situation detection sensor.
  • the gain G 2 of the second coefficient circuit III 15 included in the feed forward signal operating means III 1 is increased when the gain G 1 of the first coefficient circuit III 12 is large. However, when the gain G 1 of the first coefficient circuit III 12 is small, the gain G 2 is decreased accordingly.
  • the gain G 2 of the second coefficient circuit III 15 for correcting the magnitude of the differential value of the steering angle is increased to reduce understeering so as not to cause degradation of the vehicle dynamic characteristics, i.e., excessive turning of the steering wheel, on the basis of the signals for the vehicle travel state variable with the vehicle travel and output from the vehicle state detection sensor VI and/or the signals for state variables representing outside environmental situations and output from the outside environmental situation detection sensor VII.
  • the fourth mode of the present invention is shown in the block diagram of Fig. 7.
  • the gain changing means 111 4 is connected to the first, second, and third coefficient circuits III 12 , III 15 , and III 21 .
  • the coefficients of the first, second, and third coefficient circuits III 12 , III 15 , and III 21 can be changed on the basis of the signals for vehicle travel state variables with the vehicle travel and output from the vehicle travel state detection sensor and/or the signals for state variables representing outside environmental situations and output from the outside environmental state detection sensor.
  • the gain G 3 of the third coefficient circuit 111 21 included in the feedback signal operating means 111 2 is decreased when the gains G, and G 2 of the first and second coefficient circuits III 12 and III 15 included in the feed forward signal operating means III 1 are large, i.e., when the vehicle behavior response to the detected steering angle applied by the driver is high.
  • the gains G, and G 2 of the first and second coefficient circuits III 12 and III 15 in the feed forward signal operating means III 1 are small, i.e., when the vehicle behavior response to the steering angle applied by the driver is low, the gain G 3 of the third coefficient circuit III 21 in the feedback signal operating means III 2 is increased. Therefore, a better control effect than the third mode of the present invention can be obtained.
  • the fourth mode of the present invention is shown in the block diagram of Fig. 8.
  • the gain changing means III 4 is connected to the vehicle state detection sensor Vl and/or the outside environmental situation detection sensor VII, and the steering sensor I and/or the steering angular velocity signal operating circuit III 16 .
  • the coefficients or gains (G 1 to G 3 ) of the first to third coefficient circuits can be changed on the basis of the signals for vehicle travel state variable with the vehicle travel and output from the vehicle state detection sensor VI and/or the signals for state variables representing the outside environmental situations and output from the outside environmental situation detection sensor VII, and the steering angle signal from the steering sensor I and/or the steering angular velocity signal from the steering angular velocity signal operating circuit III 16 .
  • the feed forward signal operating means III 1 in the control means III calculates the control signal on the basis of the steering angle of the steering wheel.
  • the control signal calculated on the basis of the variables representing the vehicle behaviors is calculated by the feedback signal operating means III 2 .
  • These control signals are processed by the control signal operating means III 3 , thereby generating an optimal steering angle.
  • the optimal gains of the firstand second coefficient circuits II 2 and II 15 in the feed forward signal operating means III 1 and the third coefficient circuit III 21 in the feedback signal operating means III 2 are set by the gain changing means III 4 in the control means III.
  • gains are preferably not only changed by the vehicle travel state variable with the vehicle travel such as a vehicle velocity and a vehicle load and the state variables representing the outside environmental situations such as a road surface state, but also changed by the will of the driver. More preferably, the gains are automatically changed.
  • the present inventors proposed the gain changing means III 4 , for resetting the gains on the basis of the steering wheel angle and the steering velocity, both of which serve as factors for reflecting the driver's will.
  • the gain changing means 111 4 sets small gains G, and G 2 and a large gain G 3 when the steering wheel angle is small. In this case, the gain changing means 114 determines that the driver does not intend to turn the steering wheel. However, when the steering wheel angle is increased, the gain changing means 111 4 sets large gains G, and G 2 and a small G 3 . In this case, the gain changing means III 4 determines that the driver intends to turn the steering wheel. When the steering velocity is high, the gain changing means 111 4 determines that the driver wants to abruptly turn the steering wheel. In this case, the gains G i , G 2 , and G 3 are set in the same manner as in the above case wherein the steering wheel angle is large.
  • the control means III comprises the above gain changing means 111 4
  • the magnitude of the feed forward signal output from the feed forward signal operating means III 1 is kept small at a small steering wheel angle.
  • the magnitude of the feedback signal output from the feedback signal operating means 111 2 is increased. Therefore, vehicle stability can be further improved since the steering control signal includes the feedback signal as a major component.
  • the steering control signal has the feed forward signal as a major component, and therefore the response time of the vehicle can be further shortened.
  • vehicle stability and vehicle controllability can be improved by the steering wheel angle and the steering velocity, and a better control effect can be obtained.
  • a gain changing means III 4 is connected to a vehicle state detection sensor VI and/oran outside environmental situation detection sensor VII, a steering sensor I andlor a steering angular velocity signal operating circuit III 16 , and a vehicle behavior sensor II.
  • Gains (G 1 to G 3 ) of first to third coefficient circuits can be changed on the basis of the signals for vehicle travel state variable with the vehicle travel and output from the vehicle state detection sensor VI and/or the signals for state variables representing the outside environmental situations and output from the outside environmental situation detection sensor VII, the steering angle signal from the steering sensor I and/or the steering angular velocity signal from the steering angular velocity signal operating circuit III 16 , and the signals for variables representing vehicle behaviors and output from the vehicle behavior sensor II.
  • the control signal based on the vehicle travel state variable with the vehicle travel is calculated by the feed forward signal operating means III 1 in the control means III.
  • the control signal based on the variables representing vehicle behaviors is calculated by the feedback signal operating means 111 2 .
  • These control signals are processed by the control signal operating means 111 3 , thereby generating an optimal steering control signal.
  • the optimal gains G 1 and G 2 of the first and second coefficient circuits III 12 and III 15 in the feed forward signal operating means III 1 , and the optimal gain G 3 of the third coefficient circuit III 21 in the feedback signal operating means III 2 are set by the gain changing means III 4 in the control means III.
  • the control means III does not have a fail-safe function for such a failure.
  • the resultant steering control angle is different from an accurate control angle, which may endanger the driver.
  • the vehicle behaviors which cannot be measured (or estimated) by only the steering angle signal output from the steering sensor I and the steering angular velocity signal are input as information for changing the gains set by the gain changing means 111 4 . More accurate control can be therefore achieved.
  • the control effect can be greatly improved by a relatively simple mechanism for performing complicated control.
  • the seventh mode of the present invention is shown in the block diagram of Fig. 10.
  • the gain changing means 111 4 is connected to : at least one of the vehicle state detection sensor VI for detecting the signals for vehicle travel state variable with the vehicle travel such as a vehicle velocity and a vehicle load and/or the outside environmental situation detection sensor VII for detecting the signals for state variables representing the outside environmental situations such as a road surface state, rainfall, and an ambient temperature, and/or the steering sensor I and/or the steering angular velocity signal operating circuit III 16 and/or the vehicle behavior sensor II ; and the first coefficient circuit III 12 , the second coefficient circuit III 15 and/orthe third coefficient circuit 111 21 .
  • the gain changing means comprises : a sense-of-situation determining means III 41 for determining a present situation judged by the human senses on the basis of a signal of at least one of the vehicle state detection sensor VI and/or the outside environmental situation detection sensor VII and/or the steering sensor I and/or the steering angular velocity signal operating circuit III 16 and/or the vehicle behavior sensor II ; a vehicle state determining means III 42 for determining the required degree of vehicle stability and vehicle controllability on the basis of the determination result from the sense-of-situation determining means 111 41 ; and a gain deciding means 111 43 for deciding the gains G 1 to G 3 on the basis of the determination resultfrom the vehicle state determining means III 42 and outputting the optimal gains to the first coefficient circuit III 12 and/or the second coefficient circuit III 15 and/or the third coefficient circuit III 21 .
  • the gain changing means 111 4 receives at least one of the signals for vehicle travel state variable with the vehicle travel such as the vehicle velocity and the vehicle load and outputfrom the vehicle state detection sensor IV, the signals for state variables representing outside environmental situations such as a road surface state, rainfall, and an ambient temperature and output from the outside environmental situation detection sensor VII, the steering angle signal from the steering sensor I, the steering angular velocity signal from the steering angular velocity signal operating circuit III 16 , and the signals for variables representing vehicle behaviors and output from the vehicle behavior sensor II.
  • the sense-of-situation determining means III 41 determines the current situation, i.e., the degree of the vehicle velocity, the degree of the vehicle load, and the degree of the steering angle, on the basis of the input signal.
  • a necessary measure M for the vehicle response in units of behavior variables with slight ambiguity given by the situations determined by the vehicle state determining means 111 42 is calculated in accordance with conditions (1) to (8) given as follows :
  • condition (1) an expression is given such that "if the vehide velocity is relatively high (i.e., a value corresponding to the situation determined by the sense-of-situation determining means III 41 ), the controllability is prolonged accordingly".
  • the measure for the degree of vehicle velocity felt by the human senses is determined by the sense-of-situation determining means III 41 when the actual vehicle velocity is detected by the sensor.
  • the value of the degree obtained by the sense-of-situation determining means III 41 is converted into the necessary measure M (the necessary measure for response in this case) by the vehicle state determining means 111 42 provided with a function operation section III 421 ⁇
  • Gains G 1 to G 3 suitable for the current situation are decided by the gain deciding means 111 43 on the basis of the necessary measure M.
  • the corresponding gain is supplied to at least one of the first to third coefficient circuits III 12 , III 15 , and III 21 .
  • the eighth mode of the present invention is shown in the block diagram of Fig. 11.
  • the gain deciding means III 43 included in the gain changing means III 4 indudes a memory III 44 for calculating the gains on the basis of the necessary measure for vehicle stability and vehicle response and storing the calculated values, and a gain selector III 45 for selecting the gain values from the memory III 44 on the basis of the determination value from the vehicle state determining means III 42 .
  • the gain deciding means III 43 receives the necessary measure forvehicle stability and response output from the vehicle state determining means III 42 .
  • the memory III 44 in the gain deciding means III 43 prestores gains G 1n to G 3n (where n is the number of gains corresponding to the necessary measures) corresponding to the calculated necessary measures.
  • the gains G 1n to G 3n are gain values for achieving optimal dynamic characteristics of the vehicle on the basis of the necessary measures for vehicle stability and response.
  • the gain selector III 45 selects the gain values suitable for the current situation on the basis of the input necessary measures.
  • the selected gains are output to the first to third coefficient circuits III 12 , III 15 , and III 21 .
  • the gain changing means III 4 can be obtained wherein the gain values corresponding to the necessary measures for vehicle stability and response can be immediately supplied to the first to third coefficient circuits III 12 , III 15 , and III 21 . As a result, flexible control corresponding to given situations can be achieved.
  • the ninth mode of the present invention is shown in the block diagram of Fig. 12.
  • the gain deciding means III 43 included in the gain changing means III 4 includes a memory III 44 for storing a stability priority gain for maximizing vehicle stability and a response priority gain for maximizing the vehicle response, and a gain calculation section 111 46 for weighting these two gains on the basis of the determination value from a vehicle state determining means 111 42 and calculating gains suitable for the current situation.
  • the gain deciding means III 43 receives the necessary measures forvehicle stability and response output from the vehicle state determining means III 42 .
  • Precalculated stability priority gains G 10 to G 30 for maximizing vehicle stability and precalculated response priority gains G 11 to G 31 for maximizing the vehicle response are stored in the memory III 44 . These priority gains are the basic gains for determining their values.
  • the gain operation section III 46 multiplies the stability priority gains G 10 to G 30 with weighting coefficients corresponding to the necessary stability measure representing the degree of stability improvement and the response priority gains G 11 to G 33 with weighting coefficients corresponding to the necessary response measure.
  • the products are added to calculate gains G 1 to G 3 , and the gains G 1 to G 3 are respectively output to the first to third coefficient circuits III 12 , III 15 , and III 21 .
  • the gain changing means 111 4 can easily supply the gain values corresponding to the necessary stability and response measures to the first to third coefficient circuits III 12 ,III 15 , and III 21 . Therefore, flexible control corresponding to given situations can be achieved. A large volume of data need not be stored in the memory III 44 , and the size of the gain changing means III 4 can be reduced. Therefore, the overall system arrangement can be compact and inexpensive, thus improving efficiency.
  • a gain changing means 111 4 comprises : a vehicle behavior state variable estimating means 111 41 for estimating the variables representing vehicle behaviors on the basis of a steering angle signal outputfrom the steering sensor I and signals for vehicle travel state variable with the vehicle travel and output from the vehicle state sensor VI ; a ⁇ estimating means III 42 for estimating friction ( ⁇ ) between the road surface and the wheel surfaces on the basis of the vehicle behavior state variable estimation signal output from the vehicle behavior state variable estimating means 111 41 and the signals for variables representing vehicle behaviors and output from the vehicle behavior sensor II ; and a coefficient circuit coefficient changing means III 43 for changing the coefficient of at least one of first, second, and third coefficient circuits III 12 , III 15 , and III 21 on the basis of the ⁇ estimation signal output from the ⁇ estimating means III 42 . Therefore, the gain changing means III 4 supplies an optimal coefficient to a corresponding coefficient circuit.
  • the vehicle behavior state variable estimating means 111 41 in the gain changing means 111 4 estimates the variables representing vehicle behaviors on the basis of the steering control signal output from the control signal operating means 111 3 and the signals for vehicle travel state variables with the vehicle travel and outputfrom the vehicle state detecting sensor VI.
  • the ⁇ estimating means III 42 estimates friction ( ⁇ ) between the road surface and the wheel surfaces on the basis of the vehicle behavior state variable estimation signal output from the vehicle behavior state variable estimating means 111 41 and the signals for variables representing vehicle behaviors such as a yaw rate and a lateral acceleration output from the vehicle behavior sensor II.
  • the coefficient circuit coefficient changing means III 43 changes the coefficient of at least one of the first, second, and third coefficient circuits III 12 , III 15 , and III 21 on the basis of the ⁇ estimation signal output from the ⁇ estimating means III 42 . Therefore, an optimal coefficient corresponding to the current situations of the wheels and/or the road surface is supplied to the corresponding coefficient circuit.
  • the coefficients (G 1 , G 2 , and G 3 ) are automatically changed on the basis of the ⁇ . estimation value so as to optimally satisfy the current situations of the wheels and/or the road surface. Zig-zag driving or a spin which is caused by oversteering by the driver can be prevented. In addition, even if the driver does not notice a change in ⁇ , safety driving can be assured. Therefore, excellent driving stability can be achieved.
  • a vehicle behavior state variable estimating means III 41 estimates the variables representing vehicle behaviors on the basis of the steering control signal output from the control signal operating means III 3 and the signals for vehicle travel state variable with the vehicle travel and output from the vehicle state detection sensor VI.
  • the ⁇ estimating means III 42 comprises comparing means III 421 for comparing the peak value of the vehicle behavior state variable estimation signal output from the vehicle behavior state variable estimating means III 41 with the peak value of the vehicle behavior state variable signal output from the vehicle behavior sensor II, and a p determining means III 422 for estimating friction ⁇ on the basis of a comparison result output from the comparing means III 421 .
  • the above peak value comparison is performed by comparing magnitudes of the peak values of the vehicle behavior state variable estimation signal and the behavior state variable signal and/or a phase dif ference between their peaks.
  • the vehicle behavior state variable estimating means III 41 estimates the variables representing vehicle behaviors on the basis of a vehicle model obtained by mathematically modeling the vehicle behaviors on the smooth road by using the steering control signal output from the control signal operating means 111 3 , the signals for vehicle travel state variables with the vehicle travel and output from the vehicle state sensor VI, and the steering control signal output from the control signal operating circuit III 31 .
  • the comparing means III 421 in the ⁇ estimating means III 42 estimates the vehicle behavior state variable estimation signal output from the vehicle behavior variable estimating means 111 41 , e.g., the yaw rate and/or the lateral acceleration generated on the smooth road for the signals representing the current steering angle, the current vehicle travel state variables with the vehicle travels, and the steering control signal, calculates peaks of the signals, calculates a peak value of the signal for variable representing the vehicle behavior such as the yaw rate or the lateral acceleration output from the vehicle behavior sensor II, and compares the calculated peakvalues. This comparison operation is performed by comparing the magnitude of the peak values and/or the phase difference between their peaks.
  • the ⁇ determining means III 422 estimates friction ⁇ on the basis of the comparison result output from the comparing means III 421 .
  • the friction ⁇ is estimated by the slip ratio of the wheels at the time of stop or start of the vehicle
  • the friction ⁇ is estimated by the variables representing the vehicle behaviors according to the present invention. Therefore, the friction ⁇ for determining the cornering forces of the wheels in the normal dynamic characteristics can be estimated.
  • the road surface change caused by a change in environmental situation during vehicle traveling can be estimated by the variables representing the vehicle behaviors.
  • the coefficients can be set in the coefficient circuits by using the estimated values. Therefore, an excellent adaptive steering control system can be arranged, and stable steering with safety can be provided.
  • a gain changing means III 4 comprises: the vehicle behavior state variable estimating means III 41 for estimating the variables representing the vehicle behaviors on the basis of the steering control signal output from the control signal operating means 111 3 and the signals forvehicle travel state variable with the vehicle travel and output from the vehicle state detection sensor Vl ; a ⁇ estimating means III 42 for estimating friction ⁇ between the wheels and the road surface on the basis of the vehicle behavior state variable estimation signal output from the vehicle behavior state variable estimating means III 41 and the vehicle behavior state variable signal output from the vehicle behavior sensor II ; slip ratio calculating means III 44 for calculating a slip ratio of each vehicle wheel on the basis of the signals for vehicle travel state variable with the vehicle travel and output from the vehicle state detection sensor VI ; and a coefficient circuit coefficient changing means III 43 for changing a coefficient of at least one of first, second, and third coefficient circuits III 12 , III 15 , and III 21 on the basis of the ⁇ estimation signal output from the ⁇ estimating
  • the vehicle behavior state variable estimating means 111 41 in the gain changing means 111 4 estimates the variables representing the vehicle behaviors on the basis of the steering control signal output from the control signal operating means 111 3 and the signals for vehicle travel state variables with the vehicle travel and output from the vehicle state detection sensor VI.
  • the ⁇ estimating means III 42 estimates friction ⁇ between each wheel and the road surface on the basis of the vehicle behavior state variable estimation signal outputfrom the vehicle behavior state variable estimating means 111 41 and the behavior state variable signal output from the vehicle behavior sensor II.
  • the slip ratio calculating means III 44 calculates a slip ratio of each wheel on the basis of the signals for vehicle travel state variables with the vehicle travel and output from the vehicle state detection sensor VI, the vehicle velocity, and the vehicle wheel velocity.
  • the coefficient circuit coefficient changing means III 43 changes a coefficient of at least one of the first, second, and third coefficient circuits III 12 , III 15 , and III 21 on the basis of the p estimation signal output from the ⁇ estimating means III 42 and the slip ratio signal output from the slip ratio calculating means III 44 .
  • the slip ratio is used as a reference for changing the gain.
  • the gains when the gains must be changed to improve stability of the vehicle so as to prevent zig-zag traveling or a spin of the vehicle at the time of start or stop of the vehicle on a road having a low friction value p or during abrupt acceleration or deceleration, the gains can be changed prior to changes in variables representing the vehicle behaviors.
  • steering control corresponding to road surface condition changes caused by changes in outside environmental situations during vehicle traveling steering control corresponding to vehicle wheel condition changes caused by changes in driving force during an acceleration or deceleration operation upon depression or release of an accelerator pedal can also be performed to improve safety of the vehicle. Therefore, vehicle handling can be further improved.
  • a gain changing means III 4 comprises: a vehicle behavior state variable estimating means III 41 for estimating the variables representing the vehicle behaviors on the basis of the steering control signal output from the control signal operating means 111 3 and the signals for vehicle travel state variables with the vehicle travel and output from the vehicle state detection sensor VI ; a ⁇ estimating means III 42 for estimating friction ⁇ on the basis of the vehicle behavior state variable estimation signal output from the vehicle behavior state variable estimating means III 41 and the vehicle behavior state variable signal output from the vehicle behavior sensor II ; a road surface shape estimating means III 45 for estimating a shape of a road surface on the basis of the signals for vehicle travel state variable with the vehicle travel and output from the vehicle state detection sensor VI ; and a coefficient circuit coefficient changing means III 43 for changing a coefficient of at least one of first, second, and third coefficient circuits III 12 , III 15 , and III 21 on the basis of the p estimation signal output from the ⁇ , estimating means 111 42 and the estimated road surface
  • the vehicle behavior state variable estimating means 111 41 in the gain changing means 111 4 estimates the vehicle travel state variables with the vehicle travel behaviors on the basis of the steering control signal output from the control signal operating means 111 3 and the signals for vehicle travel state variable with the vehicle travel and output from the vehicle state detection sensor VI.
  • the ⁇ estimating means III 42 estimates friction ⁇ on the basis of the vehicle behavior state variable estimation signal output from the vehicle behavior state variable estimating means 111 41 and the signals for variables representing the vehicle behaviors and output from the vehicle behavior sensor II.
  • the road surface shape estimating means 111 45 estimates the shape of the road surface which contacts all vehicle wheels on the basis of the vehicle velocity output from the vehicle state detection sensor VI and the signals for state variables representing a suspension displacement of each vehicle wheel and a vehicle velocity.
  • the coefficient circuit coefficient changing means III 43 changes a coefficient of at least one of the first, second, and third coefficient circuits III 12 , III 15 , and III 21 on the basis of the ⁇ estimation signal output from the ⁇ estimating means III 42 and the estimated road surface shape signal output from the road surface shape estimating means III 45 .
  • vibrations caused by bumps on the road are transmitted to the vehicle body and hence the vehicle behavior sensor.
  • the influenced signal for state variable representing a vehicle behavior is used as a steering control signal, thus causing an operation error.
  • the estimated road surface shape signal is used as a reference for the gain changing means. Therefore, stability and reliability of the steering control system for the road surface shape can be further improved.
  • optimal steering control can be provided so as to compensate for the changes in traveling road surface condition.
  • Vehicle safety can be further improved, and vehicle handling can also be improved.
  • a gain changing means III 4 comprises: a vehicle behavior state variable estimating means III 41 for estimating the vehicle travel state variables with the vehicle travel behaviors on the basis of the steering control signal output from the control signal operating means 111 3 and the signals for vehicle travel state variable with the vehicle travel and output from the vehicle state detection sensor VI ; a ⁇ estimating means III 42 for estimating friction ⁇ between the vehicle wheels and the road surface on the basis of the vehicle behavior state variable estimation signal output from the vehicle behavior state variable estimating means III 41 and the signals for variables representing the vehicle behaviors and output from the vehicle behavior sensor II ; a sensor abnormality detecting means III 46 for detecting abnormalities of the steering sensor I, the vehicle behavior sensor 11, and the vehicle state detection sensor VI ; and a coefficient circuit coefficient changing means III 43 for changing a coefficient of at least one of first, second, and third coefficient circuits III 12 ,III 15 , and III 21 on the basis of the ⁇ estimation signal output from the ⁇ estimating means III 42 and the sensor abnormal
  • the vehicle behavior state variable estimating means III 41 in the gain changing means III 4 estimates the vehicle travel state variables with the vehicle travel behaviors on the basis of the steering control signal output from the control signal operating means III 13 and the signals for vehicle travel state variable with the vehicle travel and outputfrom the vehicle detection sensor VI.
  • the ⁇ , estimating means III 42 estimates friction ⁇ between the vehicle wheels and the road surface on the basis of the vehicle behavior state variable estimation signal output from the vehicle behavior state variable estimating means 111 41 and the vehicle behavior state variable signal output from the vehicle behavior sensor II.
  • the sensor abnormality detecting means 111 46 detects abnormalities of the sensors when output values of the steering sensor I, the vehicle behavior sensor II, and the vehicle state detection sensor VI fall outside the allowable range of the preset values in view of the vehicle behavior or when the sensor outputs are compared with each other and comparison results indicate an abnormality.
  • the coefficient circuit coefficient changing means 111 43 changes a coefficient of at least one of the first, second, and third coefficient circuits III 12 , III 15 , and III 21 on the basis of the ⁇ estimation signal output from the ⁇ estimating means III 42 and the sensor abnormality detection signal output from the sensor abnormality detecting means III 46 .
  • the vehicle can be constantly kept safe even if the sensors are accidentally malfunctioned or failed, thereby improving vehicle handling.
  • a method of estimating friction ⁇ between the vehicle wheels and the road surface in an apparatus for controlling steering of wheels of a vehicle according to the present invention will be briefly exemplified.
  • Equations of motion for translating lateral motion y and yaw motion ⁇ as follows :
  • Equations (1) to (4) are synthesized as follows :
  • the yaw rate ⁇ and the lateral velocity y are expressed below in accordance with equations (5) and (6).
  • S represents a Laplacian operator.
  • the coefficients of equations (8) and (10) are calculated using the specifications of the vehicle, the vehicle velocity u o , and the front and rear wheel loads m f and m r from the vehicle state detection sensor.
  • the calculated coefficients, the driver's steering angle ⁇ f , and the front and rear wheel steering angles u f and u r are used to solve equations (8) and (10), thereby estimating an estimated yaw rate ⁇ m and an estimated lateral acceleration ⁇ m .
  • friction ⁇ is given as a value for a smooth road (e.g., 0.8 to 1.0).
  • the controllability of the yaw rate and the lateral acceleration is changed according to different friction values ⁇ even if identical steering operations are performed. For example, if the friction value ⁇ is small, the yaw rate and the lateral acceleration are decreased as compared with the case wherein the friction value ⁇ is large. In addition, the leading edge of the characteristic curves of the yaw rate and the lateral acceleration are moderate. By using this nature, the friction value y is estimated. Peak values of the estimated values ⁇ m and ⁇ m of the ideal yaw rate and the ideal lateral acceleration which are obtained on the smooth road (or an equivalent) and peak values of the detected yaw rate ⁇ and the lateral acceleration y are calculated. The magnitudes of the peak values and/or the phase difference between these peaks is compared to estimate the friction.
  • a ratio of ⁇ to ⁇ m and a ratio of ⁇ to ⁇ m are calculated by equations (11), (12), (14), and (15), and the friction value can be reduced into equation (16) or (17) below :
  • the apparatus for controlling steering of wheels of a vehicle of this embodiment is applied to an apparatus for front wheels and basically belongs to the fifth mode shown in Fig. 8.
  • the apparatus comprises a steering sensor I, a vehicle behavior sensor II, a control means III, a driving means IV, an actuator means V, a front wheel steering mechanism V 10 , and a vehicle velocity sensor VI.
  • the steering sensor I is coaxial with a steering wheel to measure a steering angle of the steering wheel, as shown in Fig. 19.
  • the vehicle behavior sensor II is mounted at the center of gravity of the vehicle body and comprises a yaw rate sensor II 1 for detecting the yaw rate ⁇ and outputting a signal representing the yaw rate ⁇ .
  • the control means III comprises a feed forward signal operating means III 1 , a feedback signal operating means III 2 , a control signal operating means III 3 , and a gain changing means III 4 .
  • the feed forward signal operating means III 1 comprises : a steering angle signal circuit III 11 for transmitting, without modifications, an electrical signal corresponding to a steering angle 8 and output from the steering sensor I ; a steering angle signal operation circuit III 13 provided with a first coefficient circuit III 12 for multiplying with G 1 the signal corresponding to the steering angle 8 and output from the steering sensor I ; a steering angular velocity signal operation circuit III 16 provided with a differentiator III 14 for calculating a signal corresponding to a steering angular velocity 8 on the basis of the signal corresponding to the steering angle 8 and output from the steering sensor I and a second coefficient circuit III 15 for multiplying with G 2 the signal corresponding to the steering angular velocity ⁇ and output from the differentiator III 14 ; and an adder III 17 for adding the signals output from the first and second coefficient circuits III 12 and III 15 and the signal output from the steering angle signal circuit III 11 .
  • the feedback signal operating means III 12 comprises a vehicle behavior state variable signal circuit III 22 provided with two coefficient circuits III 21 and 111 23 , a primary delay filter III 24 , and an adder III 25 for adding the signals output from the coefficient circuits III 21 and 111 23 .
  • the primary delay filter III 24 outputs a signal representing a pseudo yaw angle ⁇ corresponding to the yaw angle ⁇ on the basis of the signal representing the y aw rate ⁇ .
  • the yaw angle signal is integrated by an integrator 101.
  • a high-pass filter 102 having an effect shown in Fig. 20(b) is connected to the output of the integrator 101 to eliminate the above-mentioned steady deviation.
  • the arrangement in the block diagram of Fig. 20(a) can be equivalently replaced with a primary delay filter 103 and a coefficient circuit 104 as shown in Fig. 20(c).
  • the integrator 101 and the high-pass filter 102 are replaced with the primary delay filter 103 and the coefficient circuit 104 to obtain the same effect as described above.
  • the control signal operating means III 3 comprises an adder/subtracter III 31 for calculating a difference or a sum of the feed forward control signal output from the feed forward signal operating means III 1 and the feedback signal output from the feedback signal operating means 111 2 .
  • the gain changing means 111 4 comprises a microcomputer 200.
  • the microcomputer 200 comprises an input port 201 for receiving a signal corresponding to the steering angle 8, a signal corresponding to the steering angular velocity ⁇ , and a signal corresponding to the vehicle velocity u o ; an arithmetic and logic unit 202 for calculating an optimal gain ; a memory 203 for storing optical gains and algorithms for the arithmetic and logic unit 202 ; and an output port 204 for outputting an optimal gain selected by the arithmetic and logic unit 202.
  • microcomputer 200 The functions of the microcomputer 200 will be described in detail with reference to a flow chart in Fig. 21.
  • initialization is performed in program P1.
  • the operating states of all sensors are detected to check their abnormalities and set the initial values therein.
  • the steering angle 8 is read from the steering sensor I to the microcomputer 200 (P4).
  • the microcomputer 200 calculates a coefficient W 2 (P5). If the steering angle is small (e.g.,
  • the intermediate values of the coefficient W 2 are successively calculated by a proper function.
  • the coefficient W 2 may be changed in accordance with changes in vehicle velocity u o . In this case, if the vehicle velocity is low, threshold values 8 1 and 8 2 of the coefficient W 2 are set to be large. However, when the vehicle velocity is high, the threshold values 8 1 and 8 2 are set to be small.
  • the microcomputer 200 then fetches the steering angular velocity 8 output from the differentiator III 14 in the feed forward control means III 1 (P6) and calculates a coefficient W 3 (P7).
  • W 31 is determined by the steering angle ⁇ . If the steering angle ⁇ is small (
  • > ⁇ 4 25°), then W 31 ⁇ 1 is established. The intermediate values ofthe W3 1 are successively calculated by a properfunction.
  • the coefficient W 32 is determined by the steering angular velocity ⁇ . If the steering angular velocity ⁇ Bis small (
  • the coefficients W 31 and W 32 may be changed in accordance with the changes in vehicle velocity in the same manner as in the coefficient W 2 .
  • the signals from the above sensors are received and the coefficients W 1 , W 2 , and W 3 are calculated as described above. Coefficients M 1 and M 2 are then calculated (P8 and P9).
  • a truth value M is calculated using the coefficients M 1 and M 2 (P10). In this case, a larger one of the coefficients M 1 and M 2 is used.
  • Optimal gains G 1 , G 2 , G 3 , and G 4 obtained on the basis of the truth value M are output to the coefficient circuits III 12 , III 13 , III 21 , and III 22 (P11), respectively.
  • the driving means IV comprises an amplifier IV 1 for receiving the steering control signal output from the control means III, i.e., the signal corresponding to the front wheel steering angle, and converting the steering control signal into an actuator drive signal.
  • the actuator means V serves to converts the actuator drive signal from the driving means IV into a front wheel steering angle and comprises a hydraulic piston V 1 , an oil-assisted mechanism V 2 , a stepping motor V 3 , and a gear box V 4 .
  • the front wheel steering mechanism V 10 comprises front wheels 511, steering linkages 512, and rods 513.
  • the oil-assisted mechanism V 2 comprises : a hydraulic pump 501 ; a releaf valve 502 for maintaining an oil pressure at a predetermined pressure ; an accumulator 503 for suppressing variations in oil pressure in the hydraulic pump 501 ; a servo valve 504 for determining a direction for supplying an oil to the hydraulic piston V 1 ; an oil supply path 505 for supplying the oil pressure to the hydraulic piston V 1 ; an oil return path 506 for returning the oil discharged from the hydraulic piston V 1 and the oil leaking from the releaf valve 502 ; and an oil tank 507 for storing the oil used in the oil-assisted mechanism.
  • the front wheels 511 are rotatably supported on the vehicle body through the steering linkages 512, respectively.
  • the steering linkages 512 are coupled through the rods 513 and the hydraulic piston V 1 .
  • the stepping motor V 3 is controlled by a signal corresponding to the front wheel steering angle from the driving means IV.
  • the stepping motor V 3 drives the servo valve 504 and also drives the rods 513 through the gear box V 4 in the right-and-left direction.
  • the stepping motor V 3 drives the rods 513 in the right-and-left direction in response to the signal from the driving means IV.
  • the stepping motor V 3 drives the servo valve 504 to cause it to supply the compressed oil from the oil supply path 505 to one chamber of the hydraulic piston V 1 .
  • the stepping motorV 3 causes the other chamber to communicate with the oil tank 507 through the oil return path 506. Therefore, the hydraulic piston V 1 is driven to assist the force acting on the stepping motor V 3 , and the front wheels 511 can be steered in the right or left direction.
  • the vehicle velocity sensor VI is mounted on an output shaft of a vehicle transmission.
  • the sensor VI detects the vehicle velocity u 0 and outputs a signal representing the vehicle velocity u o .
  • the outputs from the steering sensor I for measuring the steering angle of the steering wheel and the vehicle behavior sensor II provided with the yaw rate sensor II 1 for outputting the yaw rate ⁇ are input to the feed forward signal operating means III 1 and the feedback signal operating means III 2 in the control means III.
  • the feed forward signal operating means III 1 classifies the input signals into the signal corresponding to the steering angle 8 and the signal corresponding to the steering angular velocity ⁇ through the differentiator III 14 . These signals are input to the input port 201 in the gain changing means III 4 together with the vehicle velocity u o from the vehicle velocity sensor VI mounted on the transmission.
  • the feedback signal operating means 111 2 classifies the input signals into the signal corresponding to the yaw rate ⁇ and the signal representing the pseudo yaw angle ⁇ through the primary delay filter III 24 .
  • the input port 201 in the gain changing means III 4 determines the vehicle state on the basis of the inputs. More specifically, the degree of the vehicle velocity u o , the degree of the steering angle 8, and the degree of the steering angular velocity ⁇ are replaced with the coefficients W 1 , W 2 and W 3 which are continuously changed between 0 and 1 so as to correspond to the human evaluation values in accordance with the following logical sequences:
  • the “improvement of stability” here indicates that the vehicle can maintain the proper route even if disturbance such as a side wind acts on the vehicle.
  • the “shortening of the controllability” here indicates that the vehicle quickly responds to the driver's operation so as to, e.g., immediately change the lane when the driver wants to detour an obstacle.
  • a contribution index, i.e., the truth value M is determined by using the maximum values of the coefficients M 1 and M 2 .
  • Optimal gain values are then determined in accordance with the truth value M.
  • the values of the optimal gains calculated by the arithmetic and logic unit 202 are output at the output port 204.
  • the adder III 17 in the feed forward signal operating means III 1 adds the steering angle signal ⁇ , a signal G 1 . ⁇ obtained by multiplying the steering angle signal with the optimal gain G 1 , and a signal G 2 . ⁇ obtained by the differential value signal ⁇ of the steering angle with the optimal gain G 2 to output a feed forward signal ⁇ +G 1 ⁇ +G 2 - ⁇ to the control signal operating means III 3 .
  • the adder III 25 in the feedback signal operating means III 2 adds a signal G 3 ⁇ ⁇ obtained by multiplying the yaw rate signal ⁇ with the optimal gain G 3 , and a signal G 4 .
  • ⁇ obtained by multiplying the pseudo yaw angle signal ⁇ with the optimal gain G 4 to output a feedback signal G3 ⁇ ⁇ +G 4 ⁇ ⁇ to the control signal operating means 111 3 .
  • the driving means IV drives the following operation control signal u to drive the actuator means V : Therefore, the front wheel steering mechanism V 10 is driven to perform predetermined steering control.
  • the front wheels 511 are steered by a constant multiple (i.e., a gear ratio of the gear box V 4 ) of the steering control signal obtained by adding the feed forward signal derived from the steering wheel steering angle ⁇ and the steering velocity ⁇ to the feedback signal derived from the vehicle yaw rate ⁇ .
  • a constant multiple i.e., a gear ratio of the gear box V 4
  • the vehicle mounted with the apparatus for controlling steering of wheels of the vehicle immediately responds to steering of the steering wheel when the driver quickly turns the steering wheel or turns it with a large steering angle at a relatively low vehicle velocity since the values of the gains G 1 , G 2 , G 3 , and G 4 output to the coefficient circuits III 12 , III 15 , III 21 , and III 23 in the control means III are adjusted to those corresponding to M ⁇ 1.
  • the driver does not instantaneously turn the steering wheel.
  • the gains G i , G 2 , G 3 , and G 4 are controlled by the gain changing means III such that the truth value M is almost zero, vehicle stability can be improved and the front wheels are driven to automatically cancel disturbance.
  • optimal dynamic characteristics of the vehicle are provided for the behaviors of the vehicle and steering of the steering wheel by the driver.
  • the apparatus is applied to the one for the front wheels and basically belongs to the sixth mode shown in Fig. 9.
  • the apparatus comprises a steering sensor I, a vehicle behavior sensor II, a control means III, a driving means IV, an actuator means V, a vehicle velocity sensor VI, and a raindrop sensor VII.
  • the vehicle behavior sensor II comprises a yaw rate sensor II 2 for detecting an angular velocity around the center of the gravity of the vehicle and a lateral acceleration sensor II 2 for measuring a lateral acceleration of the vehicle, as shown in Fig. 22.
  • the control means III comprises a feed forward signal operating means III 1 , a feedback signal operating means III 2 , a control signal operating means III 3 , and a gain changing means III 4 .
  • the feed forward signal operating means III 1 comprises : a steering angle signal circuit III 11 for transmitting an electrical signal corresponding to a steering angle ⁇ and output from the steering sensor I ; a steering angle signal operation circuit III 13 provided with a first coefficient circuit III 12 for multiplying with G 1 a signal corresponding to the steering angle 8 and output from the steering sensor I ; a steering angular velocity signal operation circuit III 16 provided with a differentiator III 11 for calculating a signal corresponding to a steering angular velocity ⁇ on the basis of the signal corresponding to the steering angle ⁇ and output from the steering sensor and a second coefficient circuit III 15 for multiplying with G 2 a signal corresponding to the steering angular velocity ⁇ and output from the differentiator III 11 ; and an adder III 17 for adding the signals output from the first and second coefficient circuits III 12 and III 15 and the signal output from the steering angle signal circuit III 11 .
  • the feedback signal operating means III 2 comprises four coefficient circuits III 21 , III 23 , III 26 . and III 27 , primary delay filters III 24 and III 28 , an integrator III 29 , and a vehicle behavior state variable signal circuit III 22 provided with three adders III 20 , III 25 , and III 30 .
  • the primary delay filter III 24 outputs a signal representing a pseudo yaw angle ⁇ corresponding to a yaw angle ⁇ on the basis of the signal representing the yaw rate ⁇ .
  • the primary delay filter III 28 outputs a signal representing a pseudo lateral displacement y corresponding to the lateral displacement y on the basis of the signal corresponding to the lateral velocity y calculated by the integrator III 29 .
  • the functions and effects of these primary delay filters III 24 and III 28 are the same as those in the first embodiment.
  • the coefficient circuits III 24 , III 23 , III 27 and III 27 multiply the corresponding signals with the yaw rate feedback gain G 3 , the yaw angle feedback gain G 4 , the lateral velocity feedback gain G 5 , and the lateral displacement feedback gain G 8 , respectively.
  • the adders III 20 , III 25 and III 30 are used to add signals output from the four coefficient circuits III 21 , III 23 , III 26 and III 27 .
  • the control signal operating means 111 3 comprises an adder/subtracter III 31 for calculating a difference or a sum of the signal output from the feed forward signal operating means III 1 and the signal output from the feedback signal operating means 111 2 .
  • the gain changing means 111 4 comprises a microcomputer 200.
  • the microcomputer 200 comprises: an input port 201 for receiving the signal corresponding to the steering angle ⁇ , the signal corresponding to the steering angular velocity ⁇ , the signal corresponding to the vehicle velocity u o , the signal corresponding to the yaw rate ⁇ , the signal corresponding to the lateral acceleration ⁇ , and the signal corresponding to the rainfall r; an arithmetic and logic unit 202 for discriminating the state of the vehicle on the basis of the inputs and calculating optimal gains ; a memory 203 for storing the optimal gains and an algorithm for the arithmetic and logic unit 202 ; and an output port 204 for outputting the optimal gains selected by the arithmetic and logic unit 202.
  • microcomputer 200 The functions of the microcomputer 200 are substantially the same as those shown in the flow chart of Fig. 21. Differences between the first and second embodiments are concentrated and described with reference to Fig. 23.
  • Programs P1 to P7 are the same as those in the first embodiment.
  • the microcomputer 200 fetches an output from the raindrop sensor VII and calculates a coefficient W 4 (P9).
  • the signals of the above sensors are fetched by the microcomputer 200, and the microcomputer 200 calculates the coefficients M 1 and M 2 (P10 and P11) after calculating the coefficients W 1 , W 2 , W 3 and W 4 .
  • the truth value M is calculated using the coefficients M 1 and M 2 (P12). A larger one of the coefficients M 1 and M 2 is used for the truth value M.
  • the steering pattern of the driver can be given as follows :
  • Equations (18) to (20) i.e., the steering patterns of the driver, and auxiliary steering variable u of the time-serial optimal front wheel steering angle signal applied to the front wheel steering system are taken into consideration
  • the equations of motion are given as follows :
  • the auxiliary steering angle is given as : where g i is a contribution coefficient for giving the optimal auxiliary steering angle u, and x l represent all possible vehicle travel state variables with the vehicle travel and the vehicle behaviors which express the motion of the vehicle. These variables include the vehicle lateral displacement, the vehicle lateral velocity, the yaw angle, the yaw rate, the steering angle of the steering wheel turned by the driver, and its steering angular velocity.
  • Output values from the yaw rate sensor II 1 and the lateral acceleration sensor II 2 i.e., the yaw rate ⁇ and the lateral acceleration y are fetched by the microcomputer 200 (P14 and P15).
  • the microcomputer 200 then fetches a steering control signal ⁇ f (P16).
  • the yaw rate y and the lateral acceleration y are divided by the steering control signal ⁇ f , (P17 and P18), and the quotients are then compared with the steady vehicle steering gains of the actual steering angle and yaw rate and the measured lateral acceleration (P19 and P20), thus outputting coefficients N 1 and N 2 (P21 and P22).
  • the coefficients N 1 and N 2 are inverse numbers obtained by dividing the quotients by the steady vehicle steering gains. If each coefficient N 1 and N 2 exceeds 1.5, it is set to be 1.5.
  • the coefficients N 1 and N 2 are multiplied with the gains G 1 to G 6 and the products are respectively output to the coefficient circuits III 12 , III 13 , III 21 , III 22 , III 23 , and III 24 (P23 and P24).
  • the driving means IV comprises a subtracter IV 1 for calculating a difference between the steering control signal output from the control means III, i.e., the signal corresponding to the front wheel steering angle, and a signal output from a rod displacement meter 514 included in the actuator means V, and an amplifier IV 2 for converting the signal output from the subtracter IV 1 into a signal to be supplied to the servo valve 525 included in the actuator means V.
  • the actuator means V converts the signal from the driving means IV into a front wheel steering angle and comprises a front wheel steering mechanism V 10 and an electrohydraulic control mechanism V 20 .
  • the front wheel steering mechanism V 10 comprises front wheels 511, steering linkages 512, rods 513, and the rod displacement meter 514.
  • the electrohydraulic control mechanism V 20 comprises a hydraulic pump 521, a releaf valve 522 for maintaining an oil pressure at a predetermined pressure, an accumulator 523 for suppressing variations in oil pressure in the hydraulic pump 521, a hydraulic piston 524, a servo valve 525 for determining a direction for supplying an oil to the hydraulic piston 524, an oil supply path 526 for supplying the oil pressure to the hydraulic piston 524, an oil return path 527 for returning the oil discharged from the hydraulic piston 524 and the oil leaking from the releaf valve 522, and an oil tank 528 for storing the oil to be used in the electrohydraulic control mechanism V 2o .
  • the front wheels 511 are rotatably supported on the vehicle body through steering linkages 512.
  • the steering linkages 512 are coupled through the rods 513 and the hydraulic piston 524.
  • the servo valve 525 is controlled by a difference between the front wheel steering angle signal from the driving means IV and the output from the control means III. In other words, the servo valve 525 is controlled by a signal corresponding to the front wheel steering angle deviation.
  • the compressed oil which is controlled at a predetermined pressure by the hydraulic pump 521, the releaf valve 522, and the accumulator 523 is supplied to one chamber of the hydraulic piston 524 through the oil supply path 526 by the servo valve.
  • the other chamber communicates with the oil tank 528 through the oil return path 527, thereby driving the hydraulic piston 524. Therefore, the front wheels 511 can be steered in the right or left direction through the rods 513 and the steering linkages 512.
  • the vehicle velocity sensor Vl is mounted on the output shaft of the transmission. This sensor VI detects the vehicle velocity u o and outputs a signal representing the vehicle velocity u o .
  • the raindrop sensor VII is located in the front portion of the vehicle body. This sensor VII detects rain- drops or a humidity and outputs a signal representing whether the road is slippery.
  • the steering sensor I and the yaw rate sensor II 1 included in the vehicle behavior sensor II are substantially the same as those in the first embodiment.
  • the vehicle behavior sensor 11 also includes a lateral acceleration sensor II 2 in addition to the yaw rate sensor II 1 .
  • the lateral acceleration sensor II 2 is used to measure a lateral acceleration of the vehicle.
  • the input port 201 in the gain changing means II 4 receives a signal corresponding to the yaw rate ⁇ and output from the yaw rate sensor II 1 in the vehicle behavior sensor II, a signal corresponding to the lateral acceleration y and output from the lateral acceleration sensor II 2 in the vehicle behavior sensor II, and a signal corresponding to the rainfall r and output from the raindrop sensor VII, in addition to the signals used in the first embodiment, i.e., the signal corresponding to the steering angle ⁇ , the signal corresponding to the steering angular velocity ⁇ , and the signal corresponding to the vehicle velocity u o .
  • the feedback signal operating means III 2 divides the input data into the signal corresponding to the yaw rate ⁇ , a signal representing a pseudo yaw angle ⁇ through the primary delay filter III 24 , a signal representing the lateral velocity y through the integrator III 29 on the basis of the signal corresponding to the lateral acceleration y, and a signal representing a pseudo lateral displacement y through the primary delay filter III 28 .
  • the input port 201 of the gain changing means 111 4 determines the state of the vehicle on the basis of the input signals.
  • the input port 201 replaces the input signals into the coefficients W 1 , W 2 , W 3 , and W 4 which continuously change between 0 and 1 so as to correspond to human evaluation values representing the degree of the vehicle velocity u o , the degree of the steering angle 8, the degree of the steering angular velocity ⁇ , and the degree of the rainfall r in the following logical sequences :
  • the “improvement of stability” here indicates that the vehicle can maintain the proper route even if disturbance such as a side wind acts on the vehicle.
  • the “shortening of the response time” here indicates that the vehicle quickly responds to the driver's operation so as to, e.g., immediately change the lane when the driver wants to detour an obstacle.
  • a contribution index, i.e., the truth value M is determined by using the maximum values of the coefficients M 1 and M 2 .
  • Optimal gain values are then determined in accordance with the truth value M.
  • the optimal gain values are calculated by the arithmetic and logic unit 202.
  • the coefficients N 1 and N 2 are calculated to weight the optimal gain values calculated by the arithmetic and logic unit 202 so as to set the response characteristics of the vehicle for the variables representing vehide behaviors constant.
  • the coefficients N 1 and N 2 are multiplied with the calculated optimal gain values to keep the vehicle response time for the steering wheel angle constant.
  • the coefficient circuits provides optimal gains for the signals ⁇ , ⁇ , ⁇ , ⁇ , y and y, respectively.
  • the feed forward signal operating means III 1 outputs the feed forward signal ⁇ +G 1 . ⁇ +G 2 . ⁇ to the control signal operating means 111 3 in the same manner as in the first embodiment.
  • the adder III 25 in the feedback signal operating means III 2 adds a signal G3 ⁇ ⁇ obtained by multiplying the yaw rate signal ⁇ with the optimal gain G 3 , a signal G 4 ⁇ ⁇ obtained by multiplying the pseudo yaw angle signal ⁇ with the optimal gain G 4 , a signal G 5 . y obtained by multiplying the lateral acceleration signal y and the optimal gain G 5 , and a signal G 6 . y obtained by multiplying thepseudo lateral displacement signal y with the optimal gain G 6 and outputs the feedback signal G 3 . ⁇ +G 4 . y+G 5 y+G 6 . y to the control signal operating means 111 3 .
  • the driving means IV drives the actuator V in accordance with the signal ⁇ f from the control signal operating means 111 3 :
  • the actuator V drives the frontwheel steering mechanism V 1 to perform predetermined steering control.
  • the variables representing the vehicle travel and the vehicle behaviors are instantaneously detected to provide optimal front wheel steering control angle ⁇ f and the coefficients g I are determined by contribution degrees.
  • An instantaneous state feedback control system including the factors of the driver can be provided. Therefore, the driver can perform optimal steering wheel angle control.
  • signals input to the control means include the rainfall r from the raindrop sensor VII, the yaw rate ⁇ , and the lateral acceleration y.
  • an auxiliary steering angle may be added to the above value.
  • the response and stability characteristics of the vehicle can be adjusted without imposing a metal load on the driver, and optimal steering angle control can be performed so as to satisfy the weather and road conditions. and optimal steering angle control can be performed so as to satisfy the weather and road conditions.
  • the apparatuses for controlling steering of wheels of a vehicle are applied to the apparatuses for controlling steering of front wheels of the vehicle in the first and second embodiments.
  • an apparatus for controlling steering of wheels of a vehicle may be applied to an apparatus for controlling steering of rear wheels of a vehicle.
  • the apparatus for controlling steering of wheels of a vehicle according to the first embodiment which belongs to the fifth and seventh modes is applied to an apparatus for controlling steering of rear wheels of a vehicle. This modification will be described with reference to Fig. 24.
  • a driving means IV comprises an amplifier IV 1 for receiving the steering control signal output from the control means III, i.e., a signal corresponding to a rear wheel steering angle, and for converting it into an actuator drive signal.
  • An actuator means V converts the signal output from the driving means IV into a rear wheel steering angle and comprises a rear wheel steering mechanism V 30 , an oil-assisted mechanism V 2 , and a stepping motor V 3 .
  • the rear wheel steering mechanism V 30 comprises rear wheels 531, knuckles 532, knuckle arms 533, rods 534, a gear box 535 and a hydraulic piston 536.
  • the oil-assisted mechanism V 2 comprises a hydraulic pump 521, a releaf valve 522 for maintaining an oil pressure at a predetermined pressure, an accumulator 523 for suppressing variations in oil pressure in the hydraulic pump 521, a servo valve 525 for determining a direction for supplying an oil to the hydraulic piston 536, an oil supply path 526 for supplying the oil pressure to the hydraulic piston 536, an oil return path 527 for returning the oil discharged from the hydraulic piston 536 and the oil leaking from the releaf valve 522, and an oil tank 528 for storing the oil to be used in the oil-assisted mechanism.
  • the rear wheels 531 are rotatably supported on the vehicle body through knuckles 532.
  • the knuckle arms 533 are coupled through the rods 534 and the hydraulic piston 536.
  • the stepping motor V 3 is operated by a signal corresponding to the rear wheel steering angle and output from the driving means IV.
  • the stepping motorV 3 drives the servo valve 525 and also drives the rods 534 through the gear box 535 in the right-and-left direction.
  • the stepping motor V 3 drives the rods 534 in the right or left direction in response to the signal from the driving means IV.
  • the compressed oil from the oil supply path 526 is supplied to one chamber of the hydraulic piston 536 upon operation of the servo valve 525.
  • the other chamber communicates with the oil tank 528 through the oil return path 527.
  • the hydraulic piston 536 is driven to assist the power acting on the stepping motor V 3 . Therefore, the rear wheels 531 can be steered in the right or left direction.
  • a front wheel steering mechanism V 10 comprises front wheels 511, steering linkages 512, rods 513, a rack 515, and a pinion 516.
  • the front wheels 511 are rotatably supported on the vehicle body through the steering linkages 512.
  • the steering linkages 512 are coupled through the rods 513 and the rack 515.
  • the pinion 516 is rotated.
  • the rotational movement of the pinion 516 is converted into linear movement by the rack 515.
  • the rods 513 can be moved in the right or left direction, thereby steering the front wheels 511 through the steering linkages 512 in the right or left direction.
  • the vehicle velocity sensor Vl is mounted on the output shaft of the transmission. This sensor Vl detects the vehicle velocity u o and outputs a signal representing the vehicle velocity u o .
  • the rear wheels 511 are steered in accordance with a steering control signal obtained by calculating a difference or a sum of the feed forward signal derived from the steering angle 8 and the steering angular velocity 8, and the feedback signal derived from the vehicle yaw rate ⁇ .
  • the same algorithms can be used, and optimal rear wheel steering angles corresponding to various states can be generated.
  • the apparatus of the second embodiment can also be applied to an apparatus for controlling steering of rear wheels of a vehicle.
  • the apparatus may be used for both the front and rear wheels, although such an application is not described above.
  • An apparatus for controlling steering of wheels of a vehicle is applied to an apparatus for controlling steering of front wheels of the vehicle.
  • This apparatus basically belongs to the eleventh mode shown in Fig. 14 and comprises a steering sensor I, a vehicle behavior sensor II, a control means III, a driving means IV, an actuator means V, and a vehicle state detection sensor VI.
  • the steering sensor I is coaxial with the steering wheel to measure a steering angle of the steering wheel, as shown in Fig. 25.
  • the vehicle behavior sensor II comprises a yaw rate sensor II 1 for detecting a yaw rate yr of the vehicle and outputting a signal representing the yaw rate yr, and a lateral acceleration sensor II 2 for detecting a lateral acceleration ⁇ of the vehicle and outputting a signal representing the lateral acceleration y.
  • the vehicle behavior sensor II is mounted at the center of gravity of the vehicle.
  • the control means III comprises a feed forward signal operating means III 1 , a feedback signal operating means 111 2 , a control signal operating means 111 3 , and a gain changing means 111 4 .
  • the feed forward signal operating means III 1 comprises : a steering angle signal circuit III 11 for transmitting, without modifications, an electrical signal corresponding to the steering angle 8 and output from the steering sensor I ; a steering angle signal operating circuit 111 13 provided with a first coefficient circuit 111 12 for multiplying with G 1 the signal corresponding to the steering angle 8 and output from the steering sensor I ; a steering angular velocity signal operating circuit III 16 provided with a differentiator III 14 for calculating a signal corresponding to a steering angular velocity ⁇ on the basis of the signal corresponding to the steering angle 8 and output from the steering sensor and a second coefficient circuit III 15 for multiplying with G 2 the signal corresponding to the steering angular velocity ⁇ and output from the differentiator III 14 ; and an adder III 17 for adding the signals output from the first and second coefficient circuits III 12 and III 15 and the signal output from the steering angle signal circuit III 11 .
  • the feedback signal operating means III 2 comprises a vehicle behavior state variable signal circuit III 22 provided with four coefficient circuits III 21 , III 23 . III 26 , and III 27 , primary delay filters III 24 , III 28 , and III 29 , an adder III 25 for adding the signals output from the coefficient circuits III 21 and III 23 , an adder III 30 for adding the signals output from the coefficient circuits III 26 and III 27 , and an adder III 20 for adding the signals output from the adders III 26 and III 30 .
  • the primary delay filter III 24 outputs a pseudo yaw angle ⁇ corresponding to a yaw angle signal ⁇ on the basis of the yaw rate signal ⁇ from the yaw rate sensor II 1 .
  • the primary delay filter III 29 oytputs a pseudo lateral velocity y corresponding to the lateral velocity y on the basis of the lateral acceleration signa from the lateral acceleration sensor 11 2 .
  • the primary delay filter 111 28 outputs a pseudo lateral displacement y corresponding to the lateral displacement y on the basis of the pseudo lateral velocity signal 3y.
  • the control signal operating means III 3 comprises an adder/subtracter III 31 for calculating a difference or a sum of a feed forward control signal output from the feed forward signal operating means III 1 and a feedback signal output from the feedback signal operating means III 2 .
  • the gain changing means 111 4 comprises a microcomputer 200.
  • the microcomputer 200 comprises : an input port 201 for receiving the signal corresponding to the yaw rate ⁇ , the signal corresponding to the vehicle velocity u o , and the signal corresponding to the steering control signal as an output from the adder/subtracter 111 31 ; an arithmetic and logic unit 202 for estimating the variables representing the vehicle behaviors and friction ⁇ between the vehicle wheels and the road surface and for calculating optimal gains as a result of estimation ; a memory 203 for storing algorithms for and operation results of the arithmetic and logic unit 202 and vehicle specifications ; and an output port 204 for outputting optimal gains selected by the arithmetic and logic unit 202.
  • microcomputer 200 The functions of the microcomputer 200 will be described in detail with reference to a flow chart in Fig. 26.
  • the programs in the microcomputer 200 are started, and initialization is performed (P1).
  • initialization routine P1 hardware such as an AID converter and a D/A converter and software such as control parameters are initialized.
  • Coefficients (equations (7) and (8) of a yaw rate estimation model, i.e., equation (8) are obtained on the basis of the vehicle velocity u o and the vehicle specifications.
  • the coefficients and the steering control signal as an output from the adder/subtracter 111 31 are used to solve equation (8), thereby obtaining an estimated value ⁇ m of the vehicle yaw rate (P3).
  • the microcomputer 200 calculates the change points (e.g., the peak values of the signals and their phases) of the corresponding signals ⁇ and ⁇ m which are respectively the yaw rate ⁇ input from the AID converter and the estimated yaw rate value ⁇ m obtained in program P3 (these signals are generated by the given steering control signal) (P4).
  • the change points e.g., the peak values of the signals and their phases
  • the friction value g is estimated by program P5 by the peak value phase difference obtained in program P4. More specifically, the peak value phase difference obtained in program P4 exceeds a given threshold value (e.g., 90°), the friction value ⁇ is determined to be small, and the flow advances to the next step. However, the peak value phase difference is smaller than the threshold value, a peak ratio ⁇ / ⁇ m is calculated.
  • the coefficients of the ⁇ estimation equation (16) are estimated by equations (7) and (13) using the vehicle specifications and the vehicle velocity u o . Equation (16) is solved using the coefficients and the peak ratio to estimate ⁇ .
  • Optimal coefficients for the ⁇ , value estimated in program P5 and the vehicle velocity u 0 are determined and are output to the coefficient circuits III 12 , III 15 , III 21 , III 23 , III 26 , and III 27 (P6). The flow then returns to program P2.
  • the driving means IV comprises a subtractor IV 1 for calculating a difference between the steering control signal output from the control means III, i.e., the signal corresponding to the front wheel steering angle and the signal output from a rod displacement meter 514 included in the actuator means V, and an amplifier IV 2 for converting the difference signal into a signal to be output to the servo valve 525 included in the actuator means V.
  • the actuator means V changes the signal from the driving means IV into a front wheel steering angle and comprises a front wheel steering mechanism V 10 and an electrohydraulic control mechanism V 20 .
  • the front wheel steering mechanism V 10 comprises front wheels 511, steering linkages 512, rods 513, and the rod displacement meter 514.
  • the electrohydraulic control mechanism V 20 comprises a hydraulic pump 521, a releaf valve 522 for maintaining an oil pressure at a predetermined pressure, an accumulator 523 for suppressing variations in oil pressure in the hydraulic pump 521, a hydraulic piston 524, a servo valve 525 for determining a direction for supplying an oil to the hydraulic piston 524, an oil supply path 526 for supplying the oil pressure to the hydraulic piston 524, an oil return path 527 for returning the oil discharged from the hydraulic piston 524 and the oil leaking from the releaf valve 522, and an oil tank 528 for storing the oil to be used in the electrohydraulic control mechanism V 2o .
  • the front wheels 511 are rotatably supported on the vehicle body through the steering linkages 512.
  • the steering linkages 512 are coupled through the rods 513 and the hydraulic piston 524.
  • the servo valve 525 is controlled by a signal corresponding to a difference between the front wheel steering angle signal from the driving means IV and the output from the control means III. In other words, the servo valve 525 is controlled by the front wheel steering angle deviation signal.
  • the compressed oil which is controlled at a predetermined pressure by the hydraulic pump 521, the releaf valve 522, and the accumulator 523 is supplied to one chamber of the hydraulic piston 524 through the oil supply path 526 by the servo valve.
  • the other chamber communicates with the oil tank 528 through the oil return path 527 to drive the hydraulic piston 524.
  • the front wheels 511 can be steered in the right or left direction through the rods 513 and the steering linkages 512.
  • the vehicle state detection sensor VI comprises a vehicle velocity sensor mounted on the output shaft of the transmission.
  • the vehicle velocity sensor detects the vehicle velocity u o and outputs a signal representing the vehicle velocity u o .
  • the outputs from the steering sensor I for measuring the steering angle of the steering wheel and the vehicle behavior sensor II provided with the yaw rate sensor for outputting the yaw rate V and the lateral acceleration sensor II 2 for measuring a lateral acceleration of the vehicle are input to the feed forward signal operating means III 1 and the feedback signal operating means III 2 in the control means III.
  • the feed forward signal operating means III 1 divides the input signals into the signal corresponding to the steering angle ⁇ , and the signal corresponding to the steering angular velocity ⁇ through the differentiator III 14 .
  • the feedback signal operating means III 2 divides the input signals into the signal corresponding to the yaw rate ⁇ , a signal representing a pseudo yaw angle ⁇ through the primary delay filter III 24 , a signal representing a pseudo lateral velocity y through the primary delay filter III 29 on the basis of the signal corresponding to the lateral acceleration ⁇ , and a signal representing a pseudo lateral displacement y through the primary delay filter III 28 .
  • the input port 201 in the gain changing means III 4 receives the signal corresponding to the yaw rate ⁇ and output from the yaw rate sensor II 1 in the vehicle behavior sensor and the signal corresponding to the lateral acceleration ⁇ and output from the lateral acceleration sensor II 2 in addition to the signal corresponding to the steering control signal and output from the adder/subtracter III 31 and the signal corresponding to the vehicle velocity u o .
  • the gain changing means 111 4 estimates the yaw rate of the vehicle on the basis of the input signals, compares the estimated value with the peak value of the actual yaw rate to estimate ⁇ , and calculates optimal gains corresponding to the current vehicle states by using the estimated ⁇ value and the vehicle velocity u o .
  • the adder III 17 in the feed forward signal operating means III 1 adds a signal G 1 . 8 obtained by multiplying the steering angle signal 6 with the optimal gain G 1 and a signal G 2 .
  • ⁇ obtained by multiplying the differential value signal ⁇ of the steering angle with the optimal gain G 2 and outputs a feed forward signal ⁇ +G 1 . ⁇ +G 2 ⁇ to the control signal operating means III 3 .
  • the adder III 26 in the feedback signal operating means III 2 adds a signal G 3 ⁇ ⁇ obtained by multiplying the yaw rate signal ⁇ with the optimal gain G 3 , a signal G 4 ⁇ ⁇ obtained by multiplying the pseudo yaw angle signal ⁇ with the optimal gain G 4 , a signal G 5 . y obtained by multiplying the pseudo lateral velocity signal y with the optimal gain G 5 , and a signal G 6 ⁇ y obtained by multiplying the pseudo lateral displacement signal y with the optimal gain G 6 and outputs a feedback signal G 3 ⁇ +G 4 ⁇ +G 5 .y+G 6 .y to the control signal operating means 111 3 .
  • the driving means IV drives the actuator means V in accordance with the steering control signal ⁇ f from the control signal operating means 111 3 :
  • the actuator V drives the front wheel steering mechanism V 10 to perform predetermined steering control.
  • the optimal front wheel steering control angles ⁇ f instantaneously detect the variables representing the vehicle travel and the vehicle behaviors to determine coefficients G l according to the degrees of contribution.
  • a feedback control system for instantaneous states including the factors of the driver can be arranged to perform optimal steering angle control for the vehicle driven by the driver.
  • the apparatus for controlling steering of wheels of a vehicle is applied to an apparatus for controlling steering of front wheels of a vehicle.
  • This apparatus basically belongs to the twelfth mode shown in Fig. 15 and comprises a steering sensor I, a vehicle behaviorsensor II, a control means III, a driving means IV, an actuator means V, and vehicle state detection sensors VI.
  • the vehicle behavior sensor II comprises a yaw rate sensor II 1 for detecting an angular velocity around the center of gravity of the vehicle and a lateral acceleration sensor II 2 for measuring a lateral acceleration of the vehicle, as shown in Fig. 27.
  • the control means III comprises a feed forward signal operating means III 1 , a feedback signal operating means III 2 , a control signal operating means III 3 , and a gain changing means III 4 .
  • the coefficient circuits III 21 , III 23 , III 26 and III 27 multiply the corresponding signals with a yaw rate feedback gain G 3 , a yaw angle feedback gain G 4 , a lateral velocity feedback gain G 5 and a lateral displacement feedback gain G 6 , respectively.
  • the adders III 20 , III 25 and III 30 are used to add the signals output from the four coefficient circuits III 21 , III 23 , III 26 and III 27 .
  • the control signal operating means III 3 comprises an adder/subtracter III 31 for calculating a difference or a sum of the signal output from the feed forward signal operating means III 1 and the signal output from the feedback signal operating means 111 2 .
  • the gain changing means 111 4 comprises a microcomputer 200.
  • the microcomputer 200 comprises: an input port 201 for receiving the signal corresponding to the yaw rate ⁇ , the signal corresponding to the vehide velocity u o , the signal corresponding to each vehicle wheel angular velocity, the signal corresponding to each vehicle wheel load, and the signal corresponding to the steering control signal as an output from the adder/subtracter III 31 ; an arithmetic and logic unit 202 for estimating signals for variables representing vehicle behaviors and the ⁇ value between the vehicle wheels and the road surface, for calculating the slip ratios of the wheels on the basis of the respective input signals, and for calculating optimal gains as a result of the above estimation operations; a memory 203 for storing vehicle specifications, and algorithms and operation results of the arithmetic and logic unit 202 ; and an output port 204 for outputting the optimal gains selected by the arithmetic and logic unit 202.
  • microcomputer 200 The functions of the microcomputer 200 will be described with reference to a flow chart in Fig. 28.
  • initialization routine P21 hardware such as an AID converter and a D/A converter and software such as control parameters are initialized.
  • the coefficients (equations (7) and (8)) of yaw rate estimation model (8) are calculated on the basis of the vehicle velocity u o and the vehicle specifications.
  • the resultant coefficients and the steering control signal as an output from the adder/subtracter III 31 are used to solve equation (8) to obtain an estimated value ⁇ m of the vehicle yaw rate (P23).
  • the corresponding signal change points (i.e., the peak values and their peak phase values) of the yaw rate ⁇ input from the AID converter and the estimated value ⁇ obtained in program P23 are calculated (P24).
  • the friction value ⁇ is estimated by the peak value phase difference obtained in program P24 (P25). More specifically, when the peak value phase difference obtained in program P24 exceeds a given threshold value (e.g., 90°), the microcomputer 200 determines that the friction value ⁇ is small. In this case, the flow advances to the next step. However, if the peak value phase difference is smaller than the threshold value, a peak ratio ⁇ / ⁇ is calculated.
  • the coefficient of ⁇ estimation equation (16) is calculated by equations (7) and (13) using the vehicle specifications and the vehicle velocity u o . The resultant value and the peak ratio are used to solve equation (16) to estimate ⁇ .
  • the slip ratio is calculated on the basis of the vehicle velocity u o read in program P22 and the respective vehicle wheel angular velocities (P26).
  • Optimal coefficients are selected from the map for the estimated ⁇ values obtained in P25, the slip ratios calculated in P26, and the vehicle velocity u o .
  • the selected optimal coefficients are output to the coefficient circuits III 12 , III 15 , III 21 , III 23 , III 26 and III 27 (P27), respectively.
  • the flow returns to P22.
  • program P27 is started and various initial values are set (P271).
  • the estimated ⁇ , value and the slip ratios are read (P272).
  • the state between the wheels and the road surface is determined (P273). More specifically, the estimated, ⁇ value is corrected and weighted (e.g., Fig. 30), and the corrected value is classified (e.g., Fig. 31) The slip ratios are corrected and weighted (e.g., Fig. 32). A smaller one of the resultant values is used as a decision value G ⁇ between the wheels and the road surface.
  • the vehicle velocity u o is read (P274).
  • the vehicle velocity u o is classified (e.g., Fig. 33), and the resultant value serves as G u (P275).
  • the coefficients of the coefficient circuits are determined (P276).
  • the signal G ⁇ as an output in P273 and the signal G u as an output in P275 are used to calculate the coefficients with reference to the map shown in Fig. 34.
  • the resultant optimal coefficients are output to the corresponding coefficient circuits (P277).
  • abrupt changes in coefficients decided in P276 are prevented as follows. If a difference between the current coefficients and the updated coefficient is smaller than a maximum value of a predetermined coefficient change value, the current coefficient is replaced with the updated coefficient. However, the above difference exceeds the maximum value, the coefficient updating range corresponds to the maximum value. In this case, the current coefficient is converged stepwise to an optimal coefficient Alte- natively, the updated coefficient is filtered through a stable primary delay filter which has the current coefficient as the initial value, thereby further updating the updated coefficient
  • the gain changing means 111 4 estimates the yaw rate of the vehicle on the basis of the input signals, compares the estimated value with the peak value of the actual yaw rate to estimate ⁇ , and calculates optimal gains corresponding to the current vehicle state on the basis of the estimated u value and the vehicle velocity uo.
  • These optimal gains serve as those for the signals ⁇ , ⁇ , ⁇ , ⁇ , y, and y, respectively.
  • the adder III 17 in the feed forward signal operating means III 1 adds a signal G 1 ⁇ ⁇ obtained by multiplying the steering angle signal 8 with the optimal gain G 1 and a signal G 2 ⁇ 8 obtained by multiplying the differential value signal ⁇ of the steering angle with the optimal gain G 2 and outputs a feed forward signal ⁇ +G 1 ⁇ ⁇ +G 2 ⁇ to the control signal operating means III 3 .
  • the adder III 25 in the feedback signal operating means III 2 adds a signal G 3 . ⁇ obtained by multiplying the yaw rate signal ⁇ with the optimal gain G 3 , a signal G 4 ⁇ obtained by multiplying the pseudo yaw angle signal ⁇ with the optimal gain G 4 , a signal G 5 ⁇ y obtained by multiplying the pseudo lateral velocity signal y with the optimal gain G 6 , and a signal Gg - y obtained by multiplying the pseudo lateral displacement signal y with the optimal gain G e and outputs a feedback signal G 3 ⁇ ⁇ +G 4 . +G5 ⁇ y to the control signal operating means III 3 .
  • the driving means IV drives the actuator means V in accordance with the operation control signal ⁇ f from the control signal operating means 111 3 :
  • the actuator means V drives the front wheel steering mechanism V 10 to perform predetermined steering control.
  • the optimal front wheel steering control angles ⁇ f instantaneously detect the variables representing the vehicle and the vehicle behaviors and give the coefficients G I according to the degrees of contribution, thereby constituting a feedback control system for controlling instantaneous states including the factors of the driver. Therefore, optimal steering angle control can be performed for the vehicle driven by the driver.
  • the estimated ⁇ value is determined such that the estimated value of the yaw rate generated on the smooth road is compared with the actual yaw rate.
  • an auxiliary steering angle can be added. Zig-zag traveling or a spin caused by slipping during straight driving free from the yaw rate can be prevented.
  • the dynamic characteristics of the vehicle can be automatically controlled, and optimal steering angle control corresponding to given weather and road conditions can be performed.
  • the apparatus of this embodiment is applied to an apparatus for controlling steering of front wheels of the vehicle.
  • the apparatus belongs to the eleven mode shown in Fig. 4 and comprises a steering sensor I, a vehicle behavior sensor II, a control means III, a driving means IV, an actuator means V, and a vehicle state detection sensor VI.
  • the gain changing means 111 4 comprises a microcomputer 200.
  • the microcomputer 200 comprises: an input port 201 for receiving a signal corresponding to a yaw rate W , a signal corresponding to a vehicle velocity u o , a signal corresponding to a steering control signal as an output from an adderlsubtracter 111 31 , signals corresponding to the vehicle wheel angular velocities, signals corresponding to the vehicle wheel loads, and signals corresponding to the road surface shapes ; an arithmetic and logic unit 202 for estimating vehicle behavior variables, a friction value y between each wheel and the road surface, calculating a slip ratio of each vehicle wheel, and determining the road surface shapes and abnormalities of the sensors on the basis of the input signals, and for calculating optimal gains of the above operations ; a memory 203 for storing vehicle specifications and the algorithm for and operation results of the arithmetic and logic unit 202, and an output port 204 for outputting the optimal gains selected from the arithmetic and logic unit 202
  • microcomputer 200 The functions of the microcomputer 200 will be described in detail with reference to a flow chart in Fig. 36.
  • initialization routine P31 hardware such as an AID converter and a D/A converter and software such as control parameters are initialized.
  • the microcomputer 200 receives the yaw rate yr from the yaw rate sensor II 1 , the steering control signal as an output from the adder/subtracter III 31 , the vehicle velocity u o from the sensor VI, and the vehicle wheel angular velocity and load signals and road surface shape signals or signal like road surface shape (e.g., sprung relative displacements and velocities) through the AID converter (P32).
  • the microcomputer 200 determines whether output values from the steering angle sensor and the vehicle behavior sensor are abnormal (P34). In this case, the following operations are performed to determine : (i) whether the sensor output values exceed a predetermined value which is the upper limit for possible vehicle motion ; and (ii) whether the sensor output values do not contradict with other conditions. If the above conditions are satisfied and the sensor outputs are determined to be abnormal, the flow advances to program P39 without executing the following routine.
  • the coefficients of vehicle yaw rate estimation model (8) are calculated on the basis of the vehicle velocity u o , the vehicle wheel loads, and the vehicle specifications.
  • the resultant coefficient values and the steering control signal as an output from the adder/subtracter 111 31 are used to solve equation (8) to obtain an estimated value yr m of the vehicle yaw rate (P35).
  • the corresponding signal change points (i.e., the peak values and peak phase values) of the yaw rate y r input from the AID converter and the estimated value y rm obtained in P35 are calculated (P36).
  • the friction value ⁇ is estimated by the peak value obtained in P36 (P37). More specifically, if the peak value phase difference obtained in P36 exceeds a threshold value (e.g., 90°), the microcomputer 200 determines that the friction value ⁇ , is small and the flow advances to the next step. However, the peak value phase difference is smaller than the threshold value, a peak ratio yrlyr m is calculated.
  • the coefficient of the ⁇ estimation equation (16) is calculated by equations (7) and (13) using vehicle specifications and the vehicle velocity u o . The resultant coefficient value and the peak ratio are used to solve equation (16) to estimate ⁇ .
  • the slip ratios are calculated using the vehicle velocity u o read in P32 and the respective vehicle wheel angular velocities (P38).
  • Optimal coefficients are selected for the estimated ⁇ values estimated in P37, the slip ratios calculated in P38, the vehicle velocity u o , the rough road determination result, and the sensor abnormality determination result and are output to the coefficient circuits 111 12 , III 15 , 111 21 , 111 23 , 111 26 , and 111 27 (P39). Thereafter, the flow returns to P32.
  • the driving means IV, the actuator means V, and the vehicle velocity detection sensor Vl o have the same arrangements as in the fourth embodiment.
  • the gain changing means 111 4 calculates optimal gains on the basis of the input signals in the same manner as in the third embodiment.
  • the vehicle behavior detection sensor erroneously detects that vehicle vibrations are not caused by vehicle motion but by the bumps or the like of the road surface.
  • the vibration detection signal is used as if it is generated by vehicle motion, and therefore, the detection signal is used for feed forward or feedback control.
  • an abnormal signal generated by sensor failures or the like is used for feed forward or feedback control to cause the operation errors in the steering control system.

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  • Steering Control In Accordance With Driving Conditions (AREA)

Claims (12)

1. Dispositif de commande du braquage des roues d'un véhicule comprenant :
- un capteur de braquage (I) pour détecter l'angle de braquage d'un volant de braquage ;
- un capteur de comportement du véhicule (II) pour détecter des variables représentant des comportements du véhicule ;
- des moyens de commande (III) comprenant des moyens d'exploitation d'un signal d'action (III1) munis d'un circuit de signal d'angle de braquage (III11) pour transmettre, sans modification, un signal d'angle de braquage issu dudit capteur de braquage, caractérisé en ce que les moyens supplémentaires suivants sont prévus :
- un circuit d'exploitation du signal d'angle de braquage (11113), comportant un premier circuit de facteur (III12) pour multiplier le signal d'angle de braquage par un certain facteur ;
- un circuit d'exploitation d'un signal de vitesse angulaire de braquage (III16), comportant un différentiateur (III14) pourcalculerun signal de vitesse angulaire de braquage à partir du signal d'angle de braquage, et un second circuitdefacteur(III15) pourmultiplierle signal de vitesse angulaire de braquage par un certain facteur, etun additionneur (III17) pour additionner les signaux issus du circuit de signal d'angle de braquage, du circuit d'exploitation du signal d'angle de braquage, et du circuit d'exploitation du signal de vitesse angulaire de braquage, pour produire un signal somme, le signal somme étant produit comme signal d'action, des moyens d'exploitation d'un signal de rétroaction (III2) munis d'un circuit d'exploitation (III22) du signal de variable d'état de comportement du véhicule, comportant un troisième circuit de facteur (11121) pour multiplier par un certain facteur les signaux correspondant aux variables représentant des comportements du véhicule et issus dudit capteur de comportement du véhicule, ce circuit d'exploitation du signal de variable d'état de comportement du véhicule produisant un signal comme signal de rétroaction ; et
- des moyens d'exploitation du signal de commande (III3) munis d'un additionneur/soustracteur (III31) pour calculer une différence ou une somme de signaux issus des moyens d'exploitation du signal d'action et des moyens d'exploitation du signal de rétroaction, et pour produire un signal de commande de braquage;
- des moyens d'attaque (IV) pour amplifier la puissance du signal de commande de braquage comme sortie desdits moyens de commande, et des moyens d'actionnement (V) pour appliquer un angle de braquage optimum des roues avant ou arrière ou des deux, sur la base d'une sortie desdits moyens d'attaque.
2. Dispositif conforme à la revendication 1, comprenant de plus un capteur de détection de l'état du véhicule (VI) pour détecter l'état de déplacement du véhicule, variable avec le déplacement du véhicule, dans lequel lesdits moyens de commande (III) comprennent des moyens de changement du gain (1114), reliés au capteur de détection de l'état du véhicule (VI) et audit premier circuit de facteur (III12) pour changer le facteur dudit premier circuit de facteur (III12) sur la base des signaux d'état de déplacement du véhicule, variables avec le déplacement du véhicule, issus dudit capteur de détection de l'état du véhicule (VI).
3. Dispositif conforme à la revendication 2, comprenant de plus un capteur de détection (VII) de la situation de l'environnement extérieur pour détecter les variables d'état représentant les situations de l'environnement extérieur, dans lequel lesdits moyens de commande comprennent des moyens de changement du gain (1114), reliés au capteur de détection de l'état du véhicule (VI) et/ou au capteur de détection (VII) de la situation de l'environnement extérieur et au circuit de premier facteur (III12) pour changer le facteur dudit circuit de premier facteur (III12) sur la base des signaux d'état de déplacement du véhicule, variables avec le déplacement du véhicule et issus dudit capteur (VI) de détection de l'état du véhicule et/ou des signaux de variables d'état représentant les situations d'environnement extérieur et issus dudit capteur de détection (VII) de la situation de l'environnement extérieur.
4. Dispositif conforme à la revendication 3, dans lequel les moyens (1114) de changement du gain comprennent des moyens de changement du gain, reliés auxdits premier et second circuits de facteur (11112 III15), sur la base des signaux d'état de déplacement du véhicule, variables avec le déplacement du véhicule et issus dudit capteur (VI) de détection de l'état du véhicule, et/ou des signaux des variables d'état représentant les situations d'environnement extérieur et issus dudit capteur de détection (VII) de la situation de l'environnement extérieur.
5. Dispositif conforme à la revendication 4, dans lequel les moyens (1114) de changement du gain comprennent des moyens de changement du gain reliés auxdits premier, second et troisième circuits de facteur (III12 III15 III21) pour changer les facteurs desdits premier, second et troisième circuits de facteur, sur la base des signaux d'état de déplacement du véhicule, variables avec le déplacement du véhicule et issus dudit capteur (VI) de détection de l'état du véhicule, et/ou des signaux des variables d'état représentant les situations d'environnement extérieur et issus dudit capteur de détection (VII) de la situation de l'environnement extérieur.
6. Dispositif conforme à la revendication 5, dans lequel les moyens (1114) de changement du gain comprennent des moyens de changement du gain reliés au capteur (VI) de détection de l'état du véhicule, et/ou au capteur (VII) de détection de la situation de l'environnement extérieur et au capteur de braquage (I) et/ou au circuit (III16) d'exploitation du signal de vitesse angulaire de braquage pour changer le facteur d'au moins l'un des circuits de facteur (III12 III15 III21) sur la base des signaux d'état de déplacement du véhicule, variables avec le déplacement du véhicule et issus dudit capteur (VI) de détection de l'état du véhicule, etlou des signaux des variables d'état représentant les situations d'environnement extérieur et issus dudit capteur de détection (VII) de l'état de l'environnement extérieur, et du signal d'angle de braquage issu du capteur de braquage (I), et/ou du signal de vitesse angulaire de braquage issu du circuit d'exploitation (III16) du signal de vitesse angulaire de braquage.
7. Dispositif conforme à la revendication 5, dans lequel les moyens (1114) de changement du gain comprennent des moyens de changement du gain reliés au capteur (VI) de détection de l'état du véhicule, etlou au capteur (VII) de situation de l'environnement extérieur, au capteur de braquage (I) et/ou au circuit (III16) d'exploitation du signal de vitesse angulaire de braquage et au capteurde comportement du véhicule (II) pour changer le facteur d'au moins l'un des circuits de facteur (III12 III15 III21) sur la base des signaux d'état de déplacement du véhicule, variables avec le déplacement du véhicule et issus dudit capteur (VI) de détection de l'état du véhicule, et/ou des signaux des variables d'état représentant les situations d'environnement extérieur, du signal d'angle de braquage issu du capteur de braquage (1), et/ou du signal de vitesse angulaire de braquage issu du circuit d'exploitation (III16) du signal de vitesse angulaire de braquage, et des signaux de variables représentant les comportements du véhicule et issus dudit capteur (II) de comportement du véhicule.
8. Dispositif conforme à l'une des revendications 3 ou 7, dans lequel les moyens (1114) de changement du gain comprennent :
- des moyens (11141) de détermination du sens de la situation, pour déterminer un état actuel de la situation d'un véhicule par référence aux sens humains, sur la base d'au moins l'un des signaux d'état de déplacement du véhicule, variables avec le déplacement du véhicule et issus dudit capteur de détection de l'état du véhicule (VI), des signaux des variables d'état représentant les situations d'environnement extérieur et issus dudit capteur de détection (VII) de la situation de l'environnement extérieur, du signal d'angle de braquage issu dudit capteur de braquage (I), du signal de vitesse angulaire de braquage issu du circuit (III16) du signal de vitesse angulaire de braquage, et des signaux des variables représentant les comportements du véhicule et issus dudit capteur de comportement du véhicule (II) ;
- des moyens de détermination de l'état du véhicule (III42) pour déterminer la nécessité de stabilisation et de commande en utilisant des fonctions pour remplacer les sorties des moyens de détermination du sens de la situation (11141) s'il y a nécessité de stabilisation et de commande ; et
- des moyens de choix du gain (III43), pour choisir les gains des valeurs de sortie desdits moyens (III42) de détermination de l'état du véhicule, et sortir les gains vers lesdits circuits de facteur.
9. Dispositif conforme à la revendication 8, dans lequel les moyens (III43) de choix du gain dans les moyens de changement du gain comprennent :
- une mémoire (11144) pour calculer les valeurs de gain pour l'optimisation du mouvement du véhicule dans un état de nécessité de stabilisation et de commande, et pour mettre en mémoire les résultats calculés ; et
- un sélecteur de gains (11145) pour choisir les gains en sélectionnant les valeurs de gains calculées dans l'état de nécessité de stabilisation et de commande, à partir de la mémoire (III44), sur la base du résultat de la détermination par les moyens (III42) de détermination de l'état du véhicule.
10. Dispositif conforme à la revendication 8, dans lequel les moyens (11143) de choix du gain dans les moyens de changement du gain comprennent une mémoire (III44) pour stocker un gain de stabilité prioritaire pour augmenter la stabilité du véhicule, et un gain de réponse prioritaire pour augmenter la réponse du véhicule, et une section de calcul du gain (11146) pour pondérer ces deux gains sur la base de la valeur déterminée par les moyens de détermination de l'état du véhicule (11142) et calculer les gains adaptés à la situation actuelle.
11. Dispositif conforme à la revendication 2, dans lequel les moyens de changement du gain (1114) comprennent :
- des moyens d'estimation (11141) des variables d'état de comportement du véhicule, pour estimer les variables représentant les comportements du véhicule sur la base du signal d'angle de braquage issu dudit capteur de braquage (I) et des signaux d'état de déplacement du véhicule, variables avec le déplacement du véhicule et issus dudit capteur (VI) de détection de l'état du véhicule ;
- des moyens d'estimation de µ (III42) pour estimer une valeur (µ) du frottement entre les roues du véhicule et la surface de la route, sur la base des moyens d'estimation d'une variable d'état du comportement du véhicule (11141) et des signaux des variables représentant les comportements du véhicule, issus du capteur de comportement du véhicule (II) ; et des moyens (III43) de changement du facteur du circuit de facteur, pour changer le facteur d'au moins l'un desdits premier, second et troisième circuits de facteur (III12, III15, III21), sur la base d'un signal µ estimé issu des moyens (III42) d'estimation de µ, un gain optimum étant fourni au moins audit premier, second ou troisième circuit de facteur.
12. Dispositif conforme à la revendication 2, dans lequel les moyens de changement du gain (1114) comprennent :
- des moyens (III41) pour estimer les variables représentant les comportements du véhicule sur la base du signal de commande de braquage issu des moyens (1113) d'exploitation du signal de commande, et des signaux d'état de déplacement du véhicule, issus dudit capteur de détection de l'état du véhicule (VI) ;
- des moyens d'estimation de µ, (III42) pour estimer une valeur de frottement sur la base des signaux d'estimation des variables d'état issus desdits moyens (III41) d'estimation de la variable d'état et des signaux des variables représentant les comportements du véhicule et issus dudit capteur (II) de comportement du véhicule ;
- des moyens de calcul du coefficient de glissement (11144) pour calculer les coefficients de glissement des roues du véhicule sur la base des signaux représentant l'état de déplacement du véhicule et issus dudit capteur de détection de l'état du véhicule (VI), et des vitesses des roues du véhicule ;
- des moyens d'estimation de la forme de la surface de la route (III45) pour estimer les formes de la surface de la route, sur la base des signaux de déplacement du véhicule, variables avec le déplacement du véhicule et issus dudit capteur de détection de l'état du véhicule (VI), et/ou des moyens (III46) de détection des anomalies des capteurs, pour détecter les anomalies dudit capteur de braquage (1), dudit capteur de comportement du véhicule (II), et dudit capteur de détection de l'état du véhicule (VI) ; et
- des moyens de changement (III43) du facteur du circuit de facteur, pour changer le facteur d'au moins l'un desdits premier, second et troisième circuits de facteur (III12, III15, III21), sur la base d'un signal µ estimé sortant des moyens (III42) d'estimation de µ, et desdits signaux de coefficient de glissement, desdits signaux de forme de la surface de la route, et/ou desdits signaux de détection des anomalies des capteurs.
EP88101474A 1987-02-03 1988-02-02 Dispositif de commande du braquage des roues d'un véhicule Expired EP0278366B1 (fr)

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Application Number Priority Date Filing Date Title
JP62023261A JP2551770B2 (ja) 1987-02-03 1987-02-03 車両の操舵制御装置
JP23261/87 1987-02-03
JP284046/87 1987-11-10
JP62284046A JP2562626B2 (ja) 1987-11-10 1987-11-10 車両の操舵制御装置

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EP0278366A1 EP0278366A1 (fr) 1988-08-17
EP0278366B1 true EP0278366B1 (fr) 1991-03-06

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DE19805737B4 (de) * 1997-02-12 2009-04-23 Honda Giken Kogyo K.K. Lenkvorrichtung für ein vierradgelenkes Fahrzeug
DE19805737B9 (de) * 1997-02-12 2009-10-15 Honda Giken Kogyo K.K. Lenkvorrichtung für ein vierradgelenktes Fahrzeug
DE19805736B4 (de) * 1997-02-12 2009-12-31 Honda Giken Kogyo K.K. Lenkvorrichtung für ein Fahrzeug
US6817437B2 (en) 2001-06-19 2004-11-16 Delphi Technologies, Inc. Steer-by wire handwheel actuator
US7036445B2 (en) 2002-02-13 2006-05-02 Delphi Technologies, Inc. Watercraft steer-by-wire system
US7404369B2 (en) 2002-02-13 2008-07-29 Delphi Technologies, Inc. Watercraft steer-by-wireless system

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US4834205A (en) 1989-05-30
EP0278366A1 (fr) 1988-08-17
DE3861868D1 (de) 1991-04-11

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